Re: Anyone understand this syntax error?

[Peter Otten]

Sean Hammond wrote:

 
 Anyone understand this?
 
 Python 2.4.4c1 (#2, Oct 11 2006, 21:51:02)
 [GCC 4.1.2 20060928 (prerelease) (Ubuntu 4.1.1-13ubuntu5)] on linux2
 Type help, copyright, credits or license for more information.
 def markdown_perl(input):
 ... Send 'input' (string) to the markdown perl script, and return
 the
 ...output from markdown (string).
 ...
 ...input: a string of markdown-formatted text, including \n's at
 the end
 ...   of lines, that will be sent to the markdown process.
 ...
 ...returns: a string of valid XHTML from markdown
 ...
 ... import tempfile
 ... import commands
 ... file = tempfile.NamedTemporaryFile()
 ... file.write(input)
 ... file.flush()
 ... return commands.getoutput('./markdown.pl '+file.name)
File stdin, line 15
  return commands.getoutput('./markdown.pl '+file.name)
  ^
 SyntaxError: invalid syntax

 
 I don't get it. Syntax seems fine to me, just a normal string
 concatenation.
 
 --

Are you perhaps mixing tabs and spaces?

 def f():
... print hello # four spaces before 'print'
... return 42 # one tab before 'return'
  File stdin, line 3
return 42
^
SyntaxError: invalid syntax

Peter
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Re: wxpython worked out but can't find api docs for download.

[Paul McGuire]

krishnakant Mane [EMAIL PROTECTED] wrote in message 
news:[EMAIL PROTECTED]
 hello all.
 finally I got the accessibility issue out from wxpython.  actually
 almost got it out, but that's another story.
 now my problem is that I can't gind a downloadable version of wxpython
 api reference for the latest version or the latest api reference at
 least.
 I found the on-line version so please don't provide the same link.
 when I opened it on line, it took about 8 minuts to get the wx package
 come up on screen with over 600 links.
 I need to have some off line reference for the wxpython api.
 I have enough documentation to get started but I don't have the
 extencive api references for events and other methods, properties and
 attributes.
 can some one point me to a .zip or .tar.gz version of the api docs for 
 wxpython?
 thanking all.
 Krishnakant.

I am just now learning wxPython, and I used epydoc to generate HTML doc for 
the classes.  To do this:
1. download and install epydoc
2. Fix bug in html.py of epydoc - line 2179 inherit should be inherited
3. Run epydoc against wx/ package directory.

You will get numerous INTERNAL ERROR: messages and indentation error 
messages, but you will end up with a directory of HTML reference docs for 
the Python classes.

-- Paul 


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Re: wxpython worked out but can't find api docs for download.

[Paul McGuire]

krishnakant Mane [EMAIL PROTECTED] wrote in message 
news:[EMAIL PROTECTED]
 hello all.
 finally I got the accessibility issue out from wxpython.  actually
 almost got it out, but that's another story.
 now my problem is that I can't gind a downloadable version of wxpython
 api reference for the latest version or the latest api reference at
 least.
 I found the on-line version so please don't provide the same link.
 when I opened it on line, it took about 8 minuts to get the wx package
 come up on screen with over 600 links.
 I need to have some off line reference for the wxpython api.
 I have enough documentation to get started but I don't have the
 extencive api references for events and other methods, properties and
 attributes.
 can some one point me to a .zip or .tar.gz version of the api docs for 
 wxpython?
 thanking all.
 Krishnakant.

Also, there is much info at the wxPython wiki: 
http://wiki.wxpython.org/index.cgi/FrontPage

-- Paul 


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twisted problem with reactor.stop()

[maxime_phan]

hello, everyone
I use twisted 1.3 in my python application.
in my program, I have one server and on client running at same time (so
2 reactor.run(installSignalHandlers=0) )
the client run in one thread and the server in an other thread (
reactor.callInThread(self.client... , reactor.callInThread(self.server
)
when I catch escape button, I make a reactor.stop() but it doesn't
seem to work and quit, and the application freeze. does anyone have any
solution to quit the application with twisted?
thanks in advance
Maxime

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Re: twisted problem with reactor.stop()

[Bjoern Schliessmann]

[EMAIL PROTECTED] wrote:

 I use twisted 1.3 in my python application.

Isn't 1.3 heavily outdated? The most recent is 2.4.

 in my program, I have one server and on client running at same
 time (so 2 reactor.run(installSignalHandlers=0) ) the client run
 in one thread and the server in an other thread ( 

- Is it absolutely necessary to use two threads?
- Why do you need two reactors running? I'm not even sure if that's
  possible or why I would want to do this.

 when I catch escape button, I make a reactor.stop() but it
 doesn't seem to work and quit, and the application freeze. does
 anyone have any solution to quit the application with twisted?

So it seems you only stop one reactor of two. The other one would
have to be stopped, too, I think.

Regards,


Björn

-- 
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The monitor is plugged into the serial port

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Re: wxpython worked out but can't find api docs for download.

[krishnakant Mane]

hi pol,
thanks for your helpful suggestion.
I tried it but nothing seams to work.
I can't get the folder containing html files as you suggested.
can you kindly attach a .zip archive of your generated folder as a
privat email to me?
I will be really thankful.
Krishnakant.
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Re: Parsing data from pyserial

[Giovanni Bajo]

Lone Wolf wrote:

   reading = ser.read(40)

Simply try ser.readline() here, or maybe ser.readline(eol=\r).

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WxPython

[Raja]

Hi,
  I am trying to develop an application which would mainly do the
following 2 things . I would like to know how it can be achieved and
also the libraries needed for it .

i)  active window tracking
 In this substate, the application records the title bar
contents of the active/foreground window
 and how long, in seconds, that that window is active/in
the foreground.  If the same window
 remains in the foreground but the title bar changes (as
happens with a web browser application)  then a new record is created
for each new window title.  If a window title is recorded that
 was previously recorded (on the same date -- see Data
Structures info in section 4.4),
 then the time should be added to the previously recorded
active time for that window title.
 -- Example --
   1) User clicks Start - app enters recording state.
   2) User opens window titled Window 1 - app looks for
any prior records for Window 1
on current date.  Finding none, it creates a new
record.
   3) User opens another window titled Window 2 - app
records total time spent in Window 1, then looks for any prior
records for Window 2 on current date.  Finding none,
   it creates a new record.
   4) User re-raises/re-activates previous window Window
1 - app records total time spent
 in  Window 2, then looks for any prior records for
Window 1 on current date.  It finds
   the record created earlier, so no new record is
created.
   5) User clicks Stop (or Exit) - the app adds the
time just spent in Window 1 to the
previously recorded time spent in Window 1.  App
then returns to ready state.
 ii) idle
 In this substate, the app has detected that the computer's
screensaver is active and no time
 will be recorded for the active/foreground window.  This
substate is entered automatically
(from the active window tracking state) when the
screensaver activates and exited
automatically (returning to the active window tracking
state) when the screensaver is
  deactivated.  Note that this substate should only be
entered if the app was in the active
window tracking state when the screensaver activated.


Awaiting Your Reply,
Thank You ,
Raja.

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Resource cleanup

[Robin Becker]

I'm thinking of using Tim Peters' excellent approach to resource clean 
up see

http://mail.python.org/pipermail/python-dev/2006-April/063425.html

 class _RealTypeResourceCleaner:
 def __init__(self, *resources):
 self.resources = resources
 
 def __del__(self):
 if self.resources is not None:
 for r in self.resources:
 r.close()
 self.resources = None
 
 # and typically no other methods are needed, or desirable, in
 # this helper class
 
 class RealType:
 def __init__(*args):
 ...
 # and then, e.g.,
 self.cleaner = _ResourceCleaner(resource1, resource2)

but am wondering exactly what 'resources' are left available when the 
r.close method is called in the __del__ method of  RealTypeResourceCleaner.

In particular, can I rely on the module globals of r still being present 
if the RealType instance is going away because the main script has 
terminated, ie if the r.close method refers to a global function is it 
guaranteed to be available when the close is called?

I guess I must be asking if referring to a global in a method is 
actually a reference to that global or does the reference only occur 
when the code is executed?

I have a vague feeling that I came across problems in the past about the 
order in which modules were finalized.
-- 
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Re: How to realize the interactive python in Eclipse?

[kilnhead]

purple wrote:
 I have installed the Eclipse and the plug-in Pydev. Also, I have add an
 python program in the external tools. When I run the python program in
 the external tools, i can type python command just like in the python
 shell.But when I finished running a python file, in the console, I
 could not type any command to check some argument generated in the
 process. Is there any way I can make it?
 thank you~~

Do you not want to run python from eclipse? If so, go to preferences
for pydev and show pydev where your python executable is. Then you can
use the debug function to look at variables.

For the external tools problem with python interactive, did you include
-i as an argument for the python interpreter?

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Re: Resource cleanup

[Diez B. Roggisch]

 but am wondering exactly what 'resources' are left available when the 
 r.close method is called in the __del__ method of  RealTypeResourceCleaner.
 
 In particular, can I rely on the module globals of r still being present 
 if the RealType instance is going away because the main script has 
 terminated, ie if the r.close method refers to a global function is it 
 guaranteed to be available when the close is called?
 
 I guess I must be asking if referring to a global in a method is 
 actually a reference to that global or does the reference only occur 
 when the code is executed?
 
 I have a vague feeling that I came across problems in the past about the 
 order in which modules were finalized.

I'm a bit on unsure ground here - so take it with a grain of salt.

It is for sure that only executing code will refer to a global - the 
mere mention of anything can't possibly create a reference (in python at 
least) - consider this simple example:

import random

def foo():
 print schroedingers_cat

if random.random()  .5:
 schroedingers_cat = I'm alive!

foo()


So I presume it can very well happen that you will lose a module when 
trying to finalize.

So most probably it is the cleverest solution to make the cleaner as 
self-contained as possible, by storing explicit references to things you 
might need in the instance itself. But I'm not sure if the transitivity 
of dependencies might not kick your ass somewhere anyhow.

All in all an interesting topic - I'd be looking forward to more 
insights, and very much liked the link you gave us.


Diez
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cursor.executemany() float error

[progman]

Data Struct:
from (string), to (string), rate (float)

when i run this:

cursor.executemany('insert into promo (`From`,`To`, `RATE`) \
values (%s,%s,%f)',  [ ('AA','BB',10.2), ('CC','DD',10.3) ] )

i got this error:
TypeError: float argument required

i checked, 10.2  10.3 , there are at the right loc.
what went wrong??

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Re: Parsing data from pyserial

[Grant Edwards]

On 2006-12-03, Lone Wolf [EMAIL PROTECTED] wrote:

 import serial

 ser=serial.Serial('com1',baudrate=115200, bytesize=8,
 parity='N', stopbits=1,xonxoff=0, timeout=1)

 ser.write(PM 1) #This sets the CMUcam to poll mode

 for i in range(0,100,1):
   ser.write(TC 016 240 100 240 016 240\r\n)
   reading = ser.read(40)
   print reading
   components = reading.split()
   print components
 ser.close

 Here is an example output: 

 M 37 79 3 4 59 124 86 25
 ['59', '123', '87', '25', 'M', '37', '79', '3', '4', '59',
 '124', '86', '25', 'M
 ']
 M 38 77 3 2 59 124 86 25
 ['39', '85', '26', 'M', '38', '77', '3', '2', '59', '124', '86',
 '25', 'M', '38'
 , '7']

 My problem is that I am trying to get each data point of the
 packet into a separate variable. Ordinarily, this would be
 easy, as I would just parse the packet, read the array and
 assign each element to a variable eg. mx = components[1].
 However, that doesn't work here because the original packet
 and the array that I got from using the split() method are
 different.

I doubt it.  Try printing `reading` instead of reading.  I
suspect that the string you're getting from ser.read() has a
carraige-return in it that you aren't seeing when you do print
reading.

 If I were to try read the array created in the first example
 output, mx would be 123 instead of 37 like it is in the
 packet. In the second example, the array is 85 while the
 packet is 38.

 As near as I can figure out, pyserial is reading a stream of
 data and helpfully rearranging it so that it fits the original
 packet format M xxx xxx xxx xxx xxx xxx xxx xxx.

No, it isn't.  I wrote the Posix low-level code that's in
pyserial.  I've used pyserial extensively on both Windows and
Linux.  It doesn't rearrange anything.

 I would have thought the split() method that I used on
 original packet (ie the reading variable) would have just
 returned an array with nine elements like the packet has. This
 is not the case, and I am at a loss about how to fix this.  

When something odd seems to be happening with strings, always
print `whatever` rather than whatever

 I've searched the archive here and elsewhere with no luck. Any
 help REALLY appreciated!


-- 
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  at   STRETCH SOCKS down at the
   visi.com7-11!!
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Re: Resource cleanup

[Robin Becker]

Diez B. Roggisch wrote:
...

 I have a vague feeling that I came across problems in the past about 
 the order in which modules were finalized.
 
 I'm a bit on unsure ground here - so take it with a grain of salt.
 
 It is for sure that only executing code will refer to a global - the 
 mere mention of anything can't possibly create a reference (in python at 
 least) - consider this simple example:
 
 import random
 
 def foo():
 print schroedingers_cat
 
 if random.random()  .5:
 schroedingers_cat = I'm alive!
 
 foo()
 

yes I guess although foo must know that schroedingers_cat is global it 
doesn't need to bring it into existence so would fail 50% of the time :)

 
 So I presume it can very well happen that you will lose a module when 
 trying to finalize.
 
 So most probably it is the cleverest solution to make the cleaner as 
 self-contained as possible, by storing explicit references to things you 
 might need in the instance itself. But I'm not sure if the transitivity 
 of dependencies might not kick your ass somewhere anyhow.

I think this must be the right approach. Either the resources or the 
cleaner should hold everything required for cleanup. Probably the 
resource is the best place.

-- 
Robin Becker
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Re: cursor.executemany() float error

[Fredrik Lundh]

progman wrote:

 cursor.executemany('insert into promo (`From`,`To`, `RATE`) \
 values (%s,%s,%f)',  [ ('AA','BB',10.2), ('CC','DD',10.3) ] )
 
 i got this error:
 TypeError: float argument required
 
 i checked, 10.2  10.3 , there are at the right loc.
 what went wrong??

posting a bit more of the traceback, and mentioning what database you're 
using might be helpful.

have you tried using %s markers for all parameters, btw?  (SQL data 
binding and %-style string formatting are two different things, after all).

/F

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Re: cursor.executemany() float error

[progman]

i am using mysql

i tried the
cursor.executemany('insert into promo (`From`,`To`, `RATE`) \
 values (%s,%s,%s)',  [ ('AA','BB',10.2), ('CC','DD',10.3) ] )

and it works.

very strange. isn't it?



Fredrik Lundh wrote:
 progman wrote:

  cursor.executemany('insert into promo (`From`,`To`, `RATE`) \
  values (%s,%s,%f)',  [ ('AA','BB',10.2), ('CC','DD',10.3) ] )
 
  i got this error:
  TypeError: float argument required
 
  i checked, 10.2  10.3 , there are at the right loc.
  what went wrong??

 posting a bit more of the traceback, and mentioning what database you're
 using might be helpful.

 have you tried using %s markers for all parameters, btw?  (SQL data
 binding and %-style string formatting are two different things, after all).
 
 /F

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Re: Parsing data from pyserial

[Si Ballenger]

On Sat, 2 Dec 2006 23:02:06 -0500, Lone Wolf
[EMAIL PROTECTED] wrote:

I'm trying to get data through my serial port from a CMUcam.
This gizmo tracks a color and returns a packet of data. The
packet has nine data points (well, really eight since the first
point is just a packet header) separated by spaces as follows: M
xxx xxx xxx xxx xxx xxx xxx xxx

Here is the code I am using (python v24):

import serial

ser=serial.Serial('com1',baudrate=115200, bytesize=8,
parity='N', stopbits=1,xonxoff=0, timeout=1)

ser.write(PM 1) #This sets the CMUcam to poll mode

for i in range(0,100,1):
   ser.write(TC 016 240 100 240 016 240\r\n)
   reading = ser.read(40)
   print reading
   components = reading.split()
   print components
ser.close

In my dealing with serial gizmos I have to put a delay between
the request sent to the gizmo and the reading of the serial input
buffer for returned data. Serial ports and gizmos need some time
to do their thing.
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Re: How to realize the interactive python in Eclipse?

[purple]

Thanks so much for your concern~~

In the preferences for pydev, I have added the python.exe in the python
interpreters, and also the system PYTHONPATH, Forced built-in libs. I
am not sure whether you mean it?
I am sorry because I am a green hand on the eclipse.

And for the external tools, I have include the -i as an argument for
the python interpreter and there is no other argument. Is there any
other argument?

Thanks so much~~


 Do you not want to run python from eclipse? If so, go to preferences
 for pydev and show pydev where your python executable is. Then you can
 use the debug function to look at variables.

 For the external tools problem with python interactive, did you include
 -i as an argument for the python interpreter?

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Deleting from a list while iterating

[Rhamphoryncus]

The problems of this are well known, and a suggestion for making this
easier was recently posted on python-dev.  However, I believe this can
be done just as well without a change to the language.  What's more,
most of the suggested methods (in my search results as well as the
suggestion itself) do not scale well, which my approach would solve.

My approach is to make a set of indexes to removed while iterating,
then use a list comprehension to filter them out after.  Timings of
this and two other common approaches follow:

setapproach = \
def func(count):
from random import random
items = [random() for i in xrange(count)]
remove = set()
for index, x in enumerate(items):
#...do something...
if x  0.5:
remove.add(index)
items = [x for index, x in enumerate(items) if index not in remove]


copyapproach = \
def func(count):
from random import random
items = [random() for i in xrange(count)]
for x in items[:]:
if x  0.5:
items.remove(x)


reverseapproach = \
def func(count):
from random import random
items = [random() for i in xrange(count)]
for index in range(len(items) - 1, -1, -1):
if items[index]  0.5:
del items[index]


 import timeit
 timeit.Timer(stmt='func(1000)', setup=setapproach).timeit(1)
0.0016040802001953125
 timeit.Timer(stmt='func(1000)', setup=copyapproach).timeit(1)
0.0085191726684570312
 timeit.Timer(stmt='func(1000)', setup=reverseapproach).timeit(1)
0.0011308193206787109

 timeit.Timer(stmt='func(1)', setup=setapproach).timeit(1)
0.021183013916015625
 timeit.Timer(stmt='func(1)', setup=copyapproach).timeit(1)
1.0268981456756592
 timeit.Timer(stmt='func(1)', setup=reverseapproach).timeit(1)
0.038264989852905273

 timeit.Timer(stmt='func(10)', setup=setapproach).timeit(1)
0.23896384239196777
 timeit.Timer(stmt='func(10)', setup=copyapproach).timeit(1)
274.57498288154602
 timeit.Timer(stmt='func(10)', setup=reverseapproach).timeit(1)
2.2382969856262207

As you can see, although reverse iteration is somewhat faster at
smaller sizes, a set is substantially faster at larger sizes, and I
believe is more readable anyway.  Copying shouldn't even be considered
unless you know the size will always be trivial ( 1000).

I'm sure there's a few other approaches that would do even better under
certain conditions.  One is a generator, if your input and output
should both be iterators.  Another is using slicing to move contiguous
sections of retained items over the removed items.  I leave both of
these as an exercise for the reader.

-- 
Adam Olsen, aka Rhamphoryncus

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Re: twisted problem with reactor.stop()

[Jean-Paul Calderone]

On 3 Dec 2006 03:16:44 -0800, [EMAIL PROTECTED] wrote:
hello, everyone
I use twisted 1.3 in my python application.
in my program, I have one server and on client running at same time (so
2 reactor.run(installSignalHandlers=0) )
the client run in one thread and the server in an other thread (
reactor.callInThread(self.client... , reactor.callInThread(self.server
)
when I catch escape button, I make a reactor.stop() but it doesn't
seem to work and quit, and the application freeze. does anyone have any
solution to quit the application with twisted?
thanks in advance
Maxime

Don't do this.  You don't need separate threads for client and server
code.  There is only one reactor, and you can only run it in one thread.
Use it for both your client and your server.

Jean-Paul
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Re: Deleting from a list while iterating

[Marc 'BlackJack' Rintsch]

In [EMAIL PROTECTED], Rhamphoryncus
wrote:

 My approach is to make a set of indexes to removed while iterating,
 then use a list comprehension to filter them out after.  Timings of
 this and two other common approaches follow:
 
 setapproach = \
 def func(count):
 from random import random
 items = [random() for i in xrange(count)]
 remove = set()
 for index, x in enumerate(items):
 #...do something...
 if x  0.5:
 remove.add(index)
 items = [x for index, x in enumerate(items) if index not in remove]
 

Why do you make it that complicated?  If you are going to build a new list
anyway, this can be done without the `set()` and just one listcomp:

  items = [x for x in items if x  0.5]

No need to iterate twice over the `items`.  The two other approaches you
gave are just needed if it's important that the elements are deleted in
place, i.e. that you don't rebind `items` to a new object.

Ciao,
Marc 'BlackJack' Rintsch

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Re: Deleting from a list while iterating

[Fredrik Lundh]

Rhamphoryncus wrote:

 As you can see, although reverse iteration is somewhat faster at
 smaller sizes, a set is substantially faster at larger sizes, and I
 believe is more readable anyway.

your set approach doesn't modify the list in place, though; it creates
a new list, in a rather roundabout way.  if modification in place isn't 
important, the normal way is of course to create a *new* list:

 items = [i for i in items if not i  0.5]

on my machine, that's about two orders of magnitude faster than your 
fast approach for n=10.

(or twice as fast, if I don't factor out the time it takes to *create* 
the original list from the benchmark).

/F

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Re: About alternatives to Matlab

[Carl Banks]

Jon Harrop wrote:
  In particular, I think you are eagerly
  allocating arrays when, in a functional language, you could just as
  easily compose closures.
 
  You are completely wrong.

 I'll give an example. If you write the Python:

   a[:] = b[:] + c[:] + d[:]

 I think that is equivalent to the ML:

   fill a (map2 ( + ) (map2 ( + ) b c) d)

 which can be deforested in ML to avoid the creation of the intermediate
 result b[:] + c[:] by using a closure to add three values at once:

   fill a (map3 (fun b c d - b + c + d) b c d)

 which will be much faster because it doesn't generate an intermediate array.

Ah, but, this wasn't about temporaries when you spoke of eagerly
allocating arrays, was it?  But yes, you're right, in this example
temporary arrays are created; arrays that Ocaml would not need.  (I
don't exactly understand why you'd need a functional language to get
this optimization, though.)

You might have guessed that you can get rid of most temporary arrays,
at the expense of readability, with numpy.  For example, replacing

d1[:] = odd[:] - C1*even[:]

with

numpy.multiply(-C1,even,d1)
numpy.add(d1,odd,d1)

eliminates the intermediate.  No unnecessary array allocations; no
closures necessary.


I'm curious whether this shared-slicing isn't, in some ways,
advantageous over the Ocaml way.  I presume that in Ocaml, the way
you'd share array data is to create a closure can apply some
operation to selected elements of the array, returning the result.  But
could this as easily modify the array in-place?  I presume a good
compiler could be able to inline the function and optimize the call to
an in-place operation, but I'm not sure how well this works in
practice.

Here's a version of D4_Transform that uses no temporary arrays (aside
from the work arrays s1, d1, and d2, which are allocated only once).
It's about 40% faster for me than the one with infix operations.  I'd
be curious how it compares to a correct Ocaml version.  (I'd still
expect Ocaml to be at least twice as fast.)

def alt_D4_Transform(x, s1=None, d1=None, d2=None):
   add = numpy.add
   multiply = numpy.multiply
   C1 = 1.7320508075688772
   C2 = 0.4330127018922193
   C3 = -0.066987298107780702
   C4 = 0.51763809020504137
   C5 = 1.9318516525781364
   if d1 == None:
  d1 = numpy.zeros(x.size/2,numpy.Float)
  s1 = numpy.zeros(x.size/2,numpy.Float)
  d2 = numpy.zeros(x.size/2,numpy.Float)
   odd = x[1::2]
   even = x[:-1:2]
   multiply(-C1,even,d1)
   add(d1,odd,d1)
   multiply(C2,d1,s1)
   add(s1,even,s1)
   d2[0] = C3 * d1[-1]
   multiply(C3,d1[:-1],d2[1:])
   add(s1,d2,s1)
   d2[0] = d1[0] + s1[-1]
   add(d1[1:],s1[:-1],d2[1:])
   multiply(C4,s1,even)
   multiply(C5,d2,odd)
   if x.size  2:

alt_D4_Transform(even,s1[0:even.size/2],d1[0:even.size/2],d2[0:even.size/2])


  It seems to
  me a big help is the ability to fold multiple array operations into a
  single loop, which is optimization a dynamically-typed language like
  Python can't easily make.  (It'd require are really smart JIT compiler
  or some concessions in dynamicity.)

 Writing a JIT to compile this kind of stuff is easy.

Eh, getting a JIT to do the optimization I spoke of in Python is not
easy.  It would be relatively easy in a statically typed language.  In
Python, it'd be tantamount to rewriting a dynamically reconfigurable
version of numpy--you'd have to duplicate numpy's complex
type-dispatching rules.

 My point is that this
 is fundamentally bad code,

Whoa, there.  I realize that for people who prefer functional
programming, with their recursively reductionist way of thinking, it
might seem as if leaving any sort of reducibility in final result is
fundamentally bad, but that's a pretty strong thing to say.

 so why bother trying to write a Python JIT? Why
 not just write in a better language for this task? Optimising within a
 fundamentally slow language seems silly to me.

Because, for most people, language choice is not a greedy maximizing of
a single issue.  Nobody who uses numpy is under the impression that it
can match a statically-typed language that is compiled to machine code
in peak performance.  (Matlab is fair game, of course.)  But speed is
not the only important thing.

I use Python because it's a excellently designed language that fits my
overall needs, and numpy because sometimes I need more speed than
vanilla Python.  Only when speed is critical (for example, 3D collision
detection) do I write an extension in a better language for the task
(i.e. C).

This is something that's quite popular in the numerically-intensive
computing community, BTW.  Many people use Python to handle boring
stuff like file I/O, memory managment, and non-critical numerical
calculations, and write C or Fortran extensions to do the
numerically-intensive stuff.



Carl Banks

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Re: Deleting from a list while iterating

[Fredrik Lundh]

Fredrik Lundh wrote:

 on my machine, that's about two orders of magnitude faster than your 
 fast approach for n=10.

oops.  forget that; it's three times faster, if you're actually creating 
the entire list, and not just a generator that will create it on demand ;-)

/F

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Re: Deleting from a list while iterating

[Martin v. Löwis]

Rhamphoryncus schrieb:
 setapproach = \
 def func(count):
 from random import random
 items = [random() for i in xrange(count)]
 remove = set()
 for index, x in enumerate(items):
 #...do something...
 if x  0.5:
 remove.add(index)
 items = [x for index, x in enumerate(items) if index not in remove]
 

This is different from the other approaches in that it doesn't
modify items. If you wanted a new list, you could incrementally
build one already in the first pass, no need to collect the
indices first (as BlackJack explains).

If you wanted in-place modification, I'd do

 newitems = []
 for x in items:
if not (x  0.5):
   newitems.append(x)
 items[:] = newitems

 copyapproach = \
 def func(count):
 from random import random
 items = [random() for i in xrange(count)]
 for x in items[:]:
 if x  0.5:
 items.remove(x)
 

This happens to work for your example, but is incorrect
in the general case: you meant to write

  del items[i+removed]

here, as .remove(x) will search the list again, looking
for the first value to remove. If your condition for
removal happens to leave some items equal to x in the
list, it would remove the wrong item. Because the numbering
changes while the iteration is in progress, you have
to count the number of removed items also.

Regards,
Martin
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Re: Deleting from a list while iterating

[Rhamphoryncus]

Marc 'BlackJack' Rintsch wrote:
 Why do you make it that complicated?  If you are going to build a new list
 anyway, this can be done without the `set()` and just one listcomp:

Fredrik Lundh wrote:
 your set approach doesn't modify the list in place, though; it creates
 a new list, in a rather roundabout way.  if modification in place isn't
 important, the normal way is of course to create a *new* list:

  items = [i for i in items if not i  0.5]

 on my machine, that's about two orders of magnitude faster than your
 fast approach for n=10.

Sorry, I should have clarified that the original post assumed you
needed info from the do something phase to determine if an element is
removed or not.  As you say, a list comprehension is superior if that
is not necessary.

--
Adam Olsen, aka Rhamphoryncus

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Re: Deleting from a list while iterating

[Fredrik Lundh]

Marc 'BlackJack' Rintsch wrote:

 No need to iterate twice over the `items`.  The two other approaches you
 gave are just needed if it's important that the elements are deleted in
 place, i.e. that you don't rebind `items` to a new object.

and even when you do, that can often be written as, e.g:

 items[:] = (i for i in items if not i  0.5)

/F

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Re: Deleting from a list while iterating

[Fredrik Lundh]

Rhamphoryncus wrote:

 Sorry, I should have clarified that the original post assumed you
 needed info from the do something phase to determine if an element is
 removed or not.  As you say, a list comprehension is superior if that
 is not necessary.

that's spelled

 out = []
 for i in items:
 ... do something ...
if i  0.5:
out.append(i)

in Python, and is only a little slower than a list comprehension, as 
written above.  if performance is really important, move the method 
lookup out of the loop:

 out = []
 append = out.append
 for i in items:
 ... do something ...
if i  0.5:
append(i)

/F

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Re: Deleting from a list while iterating

[Rhamphoryncus]

Martin v. Löwis wrote:
 Rhamphoryncus schrieb:
  setapproach = \
  def func(count):
  from random import random
  items = [random() for i in xrange(count)]
  remove = set()
  for index, x in enumerate(items):
  #...do something...
  if x  0.5:
  remove.add(index)
  items = [x for index, x in enumerate(items) if index not in remove]
  

 This is different from the other approaches in that it doesn't
 modify items. If you wanted a new list, you could incrementally
 build one already in the first pass, no need to collect the
 indices first (as BlackJack explains).

I didn't feel this distinction was worth mentioning, since oldlist[:]
= newlist is so trivial.  The only solution that really avoids making
a copy is the reverse-iteration one.


 If you wanted in-place modification, I'd do

  newitems = []
  for x in items:
 if not (x  0.5):
newitems.append(x)
  items[:] = newitems

I agree, that does seem simpler.


  copyapproach = \
  def func(count):
  from random import random
  items = [random() for i in xrange(count)]
  for x in items[:]:
  if x  0.5:
  items.remove(x)
  

 This happens to work for your example, but is incorrect
 in the general case: you meant to write

   del items[i+removed]

 here, as .remove(x) will search the list again, looking
 for the first value to remove. If your condition for
 removal happens to leave some items equal to x in the
 list, it would remove the wrong item. Because the numbering
 changes while the iteration is in progress, you have
 to count the number of removed items also.

I agree that the example I gave here sucks.  However, I copied it from
another posting as a recommended method to get removal to work *right*
(without noticing how slow it is).

There seems to have been many distinct approaches to this problem over
the years.  Hopefully we can converge on a single ideal solution (or a
few situational ones) as TOOWTDI.

-- 
Adam Olsen, aka Rhamphoryncus

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Re: best way to align words?

[Robert R.]

Oleg Batrashev a écrit :

 This means that if you have 10 sentences with 5 words in each there is
 5^10 space and time complexity. Definitelly, there are better
 algorithms from dynamic programming, but you should review your needs:
 how many sentences, words you have.

it can be few to many, actually it depends of the words i'm looking for.

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Re: Parsing data from pyserial

[Grant Edwards]

On 2006-12-03, Si Ballenger [EMAIL PROTECTED] wrote:

 In my dealing with serial gizmos I have to put a delay between
 the request sent to the gizmo and the reading of the serial input
 buffer for returned data. Serial ports and gizmos need some time
 to do their thing.

I doubt that's the issue.  He's reading with a 1-second timeout
value.

-- 
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  at   have been fun.
   visi.com
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Re: About alternatives to Matlab

[Jon Harrop]

Carl Banks wrote:
   fill a (map3 (fun b c d - b + c + d) b c d)

 which will be much faster because it doesn't generate an intermediate
 array.
 
 Ah, but, this wasn't about temporaries when you spoke of eagerly
 allocating arrays, was it?

I had thought that all of the array operations were allocating new arrays at
first but it seems that at least assignment to a slice does not.

Does:

  a[:] = b[:] + c[:]

allocate a temporary for b[:] + c[:]?

 But yes, you're right, in this example 
 temporary arrays are created; arrays that Ocaml would not need.  (I
 don't exactly understand why you'd need a functional language to get
 this optimization, though.)

I thought that functional programming could get you both the brevity of
Python's slicing and the performance of C's compilation but I was wrong.
You can get the brevity of the Python approach in C.

 You might have guessed that you can get rid of most temporary arrays,
 at the expense of readability, with numpy.  For example, replacing
 
 d1[:] = odd[:] - C1*even[:]
 
 with
 
 numpy.multiply(-C1,even,d1)
 numpy.add(d1,odd,d1)
 
 eliminates the intermediate.  No unnecessary array allocations; no
 closures necessary.

Right. Performance will probably go from 5x slower to 2x slower because
you're traversing the arrays twice instead of once.

 I'm curious whether this shared-slicing isn't, in some ways,
 advantageous over the Ocaml way.

That's exactly what I thought to start with. The author of F# is working on
getting slicing into his language but the use of slicing in this Python
benchmark corrupted my fragile little mind. Slicing is a terrible way to
approach this problem if you're using a compiled language like F#.

I first wrote an OCaml translation of the Python and wrote my own
little slice implementation. I have since looked up a C++ solution and
translated that into OCaml instead:

let rec d4_aux a n =
  let n2 = n lsr 1 in
  let tmp = Array.make n 0. in
  for i=0 to n2-2 do
tmp.(i) - a.(i*2)*.h0+.a.(i*2+1)*.h1+.a.(i*2+2)*.h2+.a.(i*2+3)*.h3;
tmp.(i+n2) - a.(i*2)*.g0+.a.(i*2+1)*.g1+.a.(i*2+2)*.g2+.a.(i*2+3)*.g3;
  done;
  tmp.(n2-1)   - a.(n-2)*.h0 +. a.(n-1)*.h1 +. a.(0)*.h2 +. a.(1)*.h3;
  tmp.(2*n2-1) - a.(n-2)*.g0 +. a.(n-1)*.g1 +. a.(0)*.g2 +. a.(1)*.g3;
  Array.blit tmp 0 a 0 n;
  if n  4 then d4_aux a (n lsr 1)

let d4 a = d4_aux a (Array.length a)

Not only is that shorter than the Python, it is much faster:

0.56s C++ (direct arrays)
0.61s F# (direct arrays)
0.62s OCaml (direct arrays)
1.38s OCaml (slices)
2.38s Python (slices)
10s Mathematica 5.1

Note that all implementations are safe (e.g. C++ uses a.at(i) instead of
a[i]).

 I presume that in Ocaml, the way 
 you'd share array data is to create a closure can apply some
 operation to selected elements of the array, returning the result.

Yes. That is certainly one way of doing it.

 But could this as easily modify the array in-place?

Absolutely. A closure would capture a reference to the array. Arrays are
mutable so you could alter the array from within the closure. In F# you
could even execute the closures concurrently to alter different parts of
the same array at the same time. I just tried that and it is actually
slower to multithread this.

 I presume a good 
 compiler could be able to inline the function and optimize the call to
 an in-place operation, but I'm not sure how well this works in
 practice.

Surprisingly well it seems: F# and OCaml are almost as fast as C/C++!

 Here's a version of D4_Transform that uses no temporary arrays (aside
 from the work arrays s1, d1, and d2, which are allocated only once).
 It's about 40% faster for me than the one with infix operations.  I'd
 be curious how it compares to a correct Ocaml version.  (I'd still
 expect Ocaml to be at least twice as fast.)

I get:

1.57s Python (in-place)

  It seems to
  me a big help is the ability to fold multiple array operations into a
  single loop, which is optimization a dynamically-typed language like
  Python can't easily make.  (It'd require are really smart JIT compiler
  or some concessions in dynamicity.)

 Writing a JIT to compile this kind of stuff is easy.
 
 Eh, getting a JIT to do the optimization I spoke of in Python is not
 easy.  It would be relatively easy in a statically typed language.  In
 Python, it'd be tantamount to rewriting a dynamically reconfigurable
 version of numpy--you'd have to duplicate numpy's complex
 type-dispatching rules.

There aren't any complicated types in the above code. In fact, there are
only two types: float and float array. Type checking is easy in this case,
compilation to C is also easy, then you just dispatch to the compiled C
code when the types are ok. You would want to write your Python code like C
code but that is shorter in this case. You may also want to flag code for
compilation manually in order to avoid the overhead of compiling code
unnecessarily.

 My point is that this is fundamentally bad code,
 
 Whoa, there.  I realize that for people 

Re: A mail from Steve Ballmer. See what Microsoft will do and follow.

[Stefan Scholl]

JustStand [EMAIL PROTECTED] wrote:
 In many ways, it was the launch of Windows 95 and Office 95 eleven
 years ago that signaled the start of this transformation. ...

Right. 11 years ago I switched from Amiga to Linux.


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Re: text adventure question

[Joe Peterson]

On 2006-12-02, Ara Kooser ghashsnaga at gmail.com wrote:
 I am working on a text adventure game for python to get back
 into python programming. My version 0.1 used only functions so
 I could get familiar with how those work. I want to move beyond
 that. I am not sure what would be a good Python way of handling
 this.  I was wondering if classes would help? What things
 should be included in the main program?

That's so funny!  I did the same thing when I was learning Python!

My cousin and I wrote some text adventure games when we were teenagers
(the code was on a TRS-80 in BASIC back then, and the BASIC program
became a kind of interpreter to interpret the adventure program files).

I re-wrote it in C, then Java, then Python.  I used it as a sort of
learning tool, and since Python is so good with strings, it became very
efficient.

I now have the code running on one of my web pages, so you can play the
games on-line:

http://www.skyrush.com/explore/

-Joe
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Re: About alternatives to Matlab

[Carl Banks]

Jon Harrop wrote:
 I had thought that all of the array operations were allocating new arrays at
 first but it seems that at least assignment to a slice does not.

 Does:

   a[:] = b[:] + c[:]

 allocate a temporary for b[:] + c[:]?

Yep.

[snip]
 Not only is that shorter than the Python, it is much faster:

 0.56s C++ (direct arrays)
 0.61s F# (direct arrays)
 0.62s OCaml (direct arrays)
 1.38s OCaml (slices)
 2.38s Python (slices)
 10s Mathematica 5.1
[snip]
 1.57s Python (in-place)

So,
optimized Python is roughly the same speed as naive Ocaml
optimized Ocaml is roughly the same speed as C++


   It seems to
   me a big help is the ability to fold multiple array operations into a
   single loop, which is optimization a dynamically-typed language like
   Python can't easily make.  (It'd require are really smart JIT compiler
   or some concessions in dynamicity.)
 
  Writing a JIT to compile this kind of stuff is easy.
 
  Eh, getting a JIT to do the optimization I spoke of in Python is not
  easy.  It would be relatively easy in a statically typed language.  In
  Python, it'd be tantamount to rewriting a dynamically reconfigurable
  version of numpy--you'd have to duplicate numpy's complex
  type-dispatching rules.

 There aren't any complicated types in the above code. In fact, there are
 only two types: float and float array.

You're vastly underestimating the complexity of numpy objects.  They
have an awful lot going on under the covers to make it look simple on
the surface.  There's all kinds of type-checking and type-conversions.
A JIT that folds loops together would have to have knowledge of that
process, and it's a lot of knowledge to have.  That is not easy.

 Type checking is easy in this case,
 compilation to C is also easy, then you just dispatch to the compiled C
 code when the types are ok. You would want to write your Python code like C
 code but that is shorter in this case. You may also want to flag code for
 compilation manually in order to avoid the overhead of compiling code
 unnecessarily.

  My point is that this is fundamentally bad code,
 
  Whoa, there.  I realize that for people who prefer functional
  programming, with their recursively reductionist way of thinking, it
  might seem as if leaving any sort of reducibility in final result is
  fundamentally bad, but that's a pretty strong thing to say.

 I was referring to the slicing specifically, nothing to do with functional
 programming. My F# and OCaml code are now basically identical to the C++
 code.

It is pretty strong thing to say that anything is fundamentally bad
just because it's not fast as something else.  Fundamental badness
ought to run deeper than some superficial, linear measure.

  so why bother trying to write a Python JIT? Why
  not just write in a better language for this task? Optimising within a
  fundamentally slow language seems silly to me.
 
  Because, for most people, language choice is not a greedy maximizing of
  a single issue.  Nobody who uses numpy is under the impression that it
  can match a statically-typed language that is compiled to machine code
  in peak performance.  (Matlab is fair game, of course.)  But speed is
  not the only important thing.

 In this specific context (discrete wavelet transform benchmark), I'd have
 said that speed was the most important thing after correctness.

So let's say I'm planning to write this complicated graphical program,
that does all sorts of stuff.  I/O, networking, database, etc.  It's a
medium throughput program, and a slow language like Python is
sufficient to run it, except for this one tiny part where I have to
transform of wave data.

Now, I was going to write the program in Python, and use the very
convenient numpy to do the transformation part.   No problem, numpy
will be fast enough for my needs.

But wait!  It's silly try to optimize code in a fundamentally slow
language!  It's vanity to even try!  I guess for the sake of getting
this little D4 transform to double in speed I'll scrap Python and write
the whole thing in OCaml.

(Or I can begrudingly admit that it's not really silly to try to
optimize a slow language.)


[snip]
 This is really great work but I can't help but wonder why the authors chose
 to use Python when other languages seem better suited. I'd like to work on
 raising people's awareness of these alternatives, and probably create some
 useful tools in the process. So I'm keen to learn what Python programmers
 would want/expect from F# and OCaml.

 What would it take to make you convert?

Them not being functional would be a good start


Carl Banks

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Re: wxpython worked out but can't find api docs for download.

[cptnwillard]

Go to:

http://wxpython.org/download.php#binaries

and in the documentation part, download both wxPython-docs and
wxPython-newdocs.

Hope this helps.

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Re: wxpython worked out but can't find api docs for download.

[cptnwillard]

Sorry, I think all you want is wxPython-newdocs, which is the
wxPython-specific documentation.

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Re: Parsing data from pyserial

[Si Ballenger]

On Sun, 03 Dec 2006 16:52:33 -, Grant Edwards
[EMAIL PROTECTED] wrote:

On 2006-12-03, Si Ballenger [EMAIL PROTECTED] wrote:

 In my dealing with serial gizmos I have to put a delay between
 the request sent to the gizmo and the reading of the serial input
 buffer for returned data. Serial ports and gizmos need some time
 to do their thing.

I doubt that's the issue.  He's reading with a 1-second timeout
value.

I would think a time delay would be needed between the below two
lines in the code if he expects to get a useable data string back
from the gizmo for the command sent to it. 

  ser.write(TC 016 240 100 240 016 240\r\n)
  reading = ser.read(40)
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Re: Parsing data from pyserial

[John Machin]

Grant Edwards wrote:

 When something odd seems to be happening with strings, always
 print `whatever` rather than whatever


:-)

Unholy perlism, Batman!

For the benefit of gentle readers who are newish and might not have
seen the ` character in Python code outside a string literal, or for
those who'd forgotten, there is a cure:

|  re.sub(r`(.*?)`, rrepr(\1), print `whatever`, `foo`, `bar`)
| 'print repr(whatever), repr(foo), repr(bar)'


:-)

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Re: Parsing data from pyserial

[Grant Edwards]

On 2006-12-03, Si Ballenger [EMAIL PROTECTED] wrote:

 In my dealing with serial gizmos I have to put a delay between
 the request sent to the gizmo and the reading of the serial input
 buffer for returned data. Serial ports and gizmos need some time
 to do their thing.

I doubt that's the issue.  He's reading with a 1-second timeout
value.

 I would think a time delay would be needed between the below two
 lines in the code if he expects to get a useable data string back
 from the gizmo for the command sent to it. 

   ser.write(TC 016 240 100 240 016 240\r\n)
   reading = ser.read(40)

No. A delay isn't needed as long as the device responds within
1 second.  The read() call will wait up to 1 second for the
first byte of the response.

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  at   REZONED!! DES MOINES has
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Re: Parsing data from pyserial

[Fredrik Lundh]

Si Ballenger wrote:


 I would think a time delay would be needed between the below two
 lines in the code if he expects to get a useable data string back
 from the gizmo for the command sent to it. 
 
   ser.write(TC 016 240 100 240 016 240\r\n)
   reading = ser.read(40)

why's that?  if the gizmo is busy doing its thing, read() will wait 
for up to one second before giving up.

/F

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Re: Parsing data from pyserial

[Grant Edwards]

On 2006-12-03, John Machin [EMAIL PROTECTED] wrote:
 Grant Edwards wrote:

 When something odd seems to be happening with strings, always
 print `whatever` rather than whatever


:-)

 Unholy perlism, Batman!

OK, make that print repr(whatever). :)

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problem formatting dates from text fields.

[krishnakant Mane]

hello all.
thanks for the help and for pointing me to the proper url for wxpython
related issues.
I am so happy that I now have a very easy gui library that can do
practically every thing with such ease (no flames intended but I was
never at so much ease with java swing ).
I however have a problem with dates.
I am tired searching for some good tutorial that can explain the basic
functionality of wx.datetime class and the datetime picker.
I want to display the date in dd/mm/ format and allow the user to
change the dates.
I then will like to take the value (the entire date) and put into a database.
now this is my first question.
the other problem is even more tough to solve with my given knowledge
of wx.datetime and related classes.
unfortunately the database given to me has a text field for date and
the data is neetly entered.
but when I get the data back from that text field I some how want to
convert it back to actual date in the same dd/mm/ format and send
this as a value to my date time picker.
how can I achieve this?
thanking all.
Krishnakant.
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please provide urls for some python success stories.

[krishnakant Mane]

hello all.
actually I have been recently appointed as a technology consulltent at
a huge company.
and I have couple more such projects in the pypeline.
unfortunately the officials out here are too much in favour of java
and I have personally worked with both and find that python is heaven
in syntax and makes it very easy to do complex things.  on speed?  I
think experts on this list can give better answer, but efficiency and
maintainance wise there is nothing like python I believe.
the problem here is that I am from India and all indians on this list
can correct me if I am wrong, very few people know about python here.
infact a vast majority of programmers ask me python? what is that!
they don't even know that it is a programming language, let alone using it.
but I am amongst the very few who have actually used both java and python.
I need some strong evidence to prove to these stupid and java oriented
officials that there is some thing better than java called python.
can some one provide me some urls or may be share some personal
experience on this issue?
I saw a couple of blogs and a few success stories on the python web site itself.
but the common answer I am getting is y! even java can do this and
java is much faster!
I am really adicted to python due to its superiority and efficiency
and the  amount of libraries.
but I need some strong official efidence.
Please help me, I don't want to leave python.
Krishnakant.
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Re: About alternatives to Matlab

[Jon Harrop]

Carl Banks wrote:
 0.56s C++ (direct arrays)
 0.61s F# (direct arrays)
 0.62s OCaml (direct arrays)
 1.38s OCaml (slices)
 2.38s Python (slices)
 10s Mathematica 5.1
 [snip]
 1.57s Python (in-place)
 
 So,
 optimized Python is roughly the same speed as naive Ocaml
 optimized Ocaml is roughly the same speed as C++

Absolutely not:

Optimized Python is 14% slower than badly written OCaml. Given the problem,
rather than the Python solution, nobody would write OCaml code like that.

Unoptimised but well-written OCaml/C/C++ is 2.5-2.8x faster than the fastest
Python so far whilst also requiring about half as much code.

Optimising the C++ by hoisting the O(log n) temporary array allocations into
one allocation makes it another 20% faster. I'm sure there are plenty more
optimisations...

 There aren't any complicated types in the above code. In fact, there are
 only two types: float and float array.
 
 You're vastly underestimating the complexity of numpy objects.  They
 have an awful lot going on under the covers to make it look simple on
 the surface.  There's all kinds of type-checking and type-conversions.
 A JIT that folds loops together would have to have knowledge of that
 process, and it's a lot of knowledge to have.  That is not easy.

My suggestion doesn't really have anything to do with numpy. If you had such
a JIT you wouldn't use numpy in this case.

That's my point, using numpy encouraged the programmer to optimise in the
wrong direction in this case (to use slices instead of element-wise
operations).

 I was referring to the slicing specifically, nothing to do with
 functional programming. My F# and OCaml code are now basically identical
 to the C++ code.
 
 It is pretty strong thing to say that anything is fundamentally bad
 just because it's not fast as something else.  Fundamental badness
 ought to run deeper than some superficial, linear measure.

The slice based approach is not only slower, it is longer, more obfuscated
and more difficult to optimise. That doesn't just apply to Python and
numpy, it also applies to Matlab, Mathematica etc.

Which begs the question, if you were writing in a compiled language like F#
would you ever use slices?

 Now, I was going to write the program in Python, and use the very
 convenient numpy to do the transformation part.

What makes numpy convenient?

 No problem, numpy will be fast enough for my needs.

Ok. But you'd rather have a compiler?

 But wait!  It's silly try to optimize code in a fundamentally slow
 language!  It's vanity to even try!  I guess for the sake of getting
 this little D4 transform to double in speed

C++ is currently 3.4x faster than Python.

 I'll scrap Python and write the whole thing in OCaml.

Why not drop to C for this one function?

 [snip]
 This is really great work but I can't help but wonder why the authors
 chose to use Python when other languages seem better suited. I'd like to
 work on raising people's awareness of these alternatives, and probably
 create some useful tools in the process. So I'm keen to learn what Python
 programmers would want/expect from F# and OCaml.

 What would it take to make you convert?
 
 Them not being functional would be a good start

They don't impose functional programming on you.

-- 
Dr Jon D Harrop, Flying Frog Consultancy
Objective CAML for Scientists
http://www.ffconsultancy.com/products/ocaml_for_scientists
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Using win32gui.SendMessage and SysListView32 control

[geskerrett]

Hope someone can steer me in the right direction.

I am trying to use python to collect the values from a Win32
application's control.
I can successfull query an retreive the values ListBox, Edit and
Buttons, however, the application uses a control called a
'SysListView32' Control.  MSDN says that this descends from CListView
control and the msdn website reference for this control is;
http://msdn2.microsoft.com/en-gb/library/ms670560.aspx
(scroll to the message constants)

This page seems to imply that the control can be queried with messages,
however, my problem seems to be that pywin32.win32con does not define a
constant for the LVM series of messages.

Any other suggestions ??

I am looking for something similar to code below which does a fine job
of collecting all of the text values from a ListBox control;

count = win32gui.SendMessage(hndl,win32con.LB_GETCOUNT)
vals = []
for i in range(count):
strlen = win32gui.SendMessage(hndl,win32con.LB_GETTEXTLEN)
text = ' '*(strlen+1) #Buffer for returned text -50
characters
lentext =
win32gui.SendMessage(hndl,win32con.LB_GETTEXT,i,text)
txt = text[0:lentext]
print Hndl: %8s  Class: %-10s  TxtLen:%3s TxtVal: %s%
(hndl,clname,lentext,txt)
vals.append(txt.strip())

Thanks in advance.

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Re: Deleting from a list while iterating

[Martin v. Löwis]

Rhamphoryncus schrieb:
 This is different from the other approaches in that it doesn't
 modify items. If you wanted a new list, you could incrementally
 build one already in the first pass, no need to collect the
 indices first (as BlackJack explains).
 
 I didn't feel this distinction was worth mentioning, since oldlist[:]
 = newlist is so trivial.  The only solution that really avoids making
 a copy is the reverse-iteration one.

The distinction is relevant for performance, as the slice assignment
has a complexity linear with the number of elements.

Whether making a copy is expensive depends on the precise data: the
solution that makes the copy in reverse may have quadratic complexity
(if the number of removed elements increases with the list size);
the version that appends all remaining elements to a new list and
then does slice assignment should behave better-than-quadratic
(in recent versions, it should give you linear performance).

Regards,
Martin
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Re: please provide urls for some python success stories.

[Mohammad Tayseer]

Hello Krishnakant
There is a book Python success stories. Download the 2 volumes from here
http://pythonology.org/success

If you want to convince java programmers to use python, show them this 
presentation from PyCon2003
The seven habits of highly  effective technology disruption
www.infoether.com/~rich/pycon2003.pdf
It shows how to use MSAgent technology in java.

Don't forget to tell them about Jython



 
-
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Thread error

[Salvatore Di Fazio]

Hi guys,
when I close the application I get the following error:

-
Traceback (most recent call last):
  File main.py, line 88, in module
while exit : pass
KeyboardInterrupt
Unhandled exception in thread started by
Error in sys.excepthook:

Original exception was:
-

This is the code:
-
# Echo client program
import socket
import sys
import thread
import mtalk

HOST = '192.168.0.115'# The remote host
PORT = 3580   # The same port as used by the server

buff = 
buffStatus = 0
s = None
exit = 1

### keywordDataIn ###
def keywordDataIn():
  global buff, buffStatus, exit
  talkmsg = mtalk.TalkMessage()
  while exit:
line = sys.stdin.readline()
if line == 'quit\n':
  exit = 0
  break
elif line != '\n':
  lock.acquire()
  buff = talkmsg.Make(line)
  buffStatus = 1
  lock.release()
elif line == '\n':
  pass

### dataToServer ###
def dataToServer():
  global buff, buffStatus, exit
  while exit:
if buffStatus == 1:
  try:
lock.acquire()
s.sendall(buff)
buff = 
buffStatus = 0
lock.release()
  except: socket.error
  pass # errore da controllare

## dataFromServer ##
def dataFromServer():
  global exit
  while exit:
data = s.recv(1024)
print 'Received', repr(data)




### Main ###
if __name__ == __main__ :

  for res in socket.getaddrinfo(HOST, PORT, socket.AF_UNSPEC,
socket.SOCK_STREAM):
af, socktype, proto, canonname, sa = res

  buffStatus = 0

  try:
s = socket.socket(af, socktype, proto)
  except socket.error, msg:
print(Unexpected error)
s = None
sys.exit(1)

  try:
s.connect(sa)
print 'Connection ...'
  except socket.error, msg:
print(The server was not reachable)
s.close()
s = None
sys.exit(1)

  print 'Connected'

  # mutex
  lock = thread.allocate_lock()
  thread.start_new_thread(keywordDataIn, ())
  thread.start_new_thread(dataToServer, ())
  thread.start_new_thread(dataFromServer, ())

  while exit : pass

  s.close()
-


Tnx

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Re: Using win32gui.SendMessage and SysListView32 control

[Neil Hodgson]

[EMAIL PROTECTED]:

 This page seems to imply that the control can be queried with messages,
 however, my problem seems to be that pywin32.win32con does not define a
 constant for the LVM series of messages.

These are defined in win32/lib/commctrl.py in my installation.

Neil
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Re: problem formatting dates from text fields.

[John Machin]

Dennis Lee Bieber wrote:
 On Mon, 4 Dec 2006 01:11:30 +0530, krishnakant Mane
 [EMAIL PROTECTED] declaimed the following in comp.lang.python:

  I am tired searching for some good tutorial that can explain the basic
  functionality of wx.datetime class and the datetime picker.
  I want to display the date in dd/mm/ format and allow the user to
  change the dates.

   Simplest is probably to do what many web-sites use for credit card
 expiration dates... Ignore any pre-built date-time modules...

   Create three integer fields, make the first two drop-down lists
 pre-populated with days and months. And validate the results later (just
 to cover someone putting in 31 02 ).


My 2 cents worth:

(1) this annoys the bejaysus out of data inputters who can type
31\t12 a lot faster than they can pick it out of two drop-down lists.

(2) this would annoy the bejaysus out of data users if they were aware
of the extent of off-by-one errors caused by using drop-down lists.

Cheers,
John

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Interface Designer

[Murdok Petrovsky]

Hi list!

I'm starting to program in python, i need a soft  interface designer and
adapt this interface to python. Somebody can help me with this?


Sorry, my english is very bad.


Regards to all.
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Re: Using win32gui.SendMessage and SysListView32 control

[[EMAIL PROTECTED]]

[EMAIL PROTECTED] schrieb:

 Hope someone can steer me in the right direction.

 I am trying to use python to collect the values from a Win32
 application's control.
 I can successfull query an retreive the values ListBox, Edit and
 Buttons, however, the application uses a control called a
 'SysListView32' Control.  MSDN says that this descends from CListView
 control and the msdn website reference for this control is;
 http://msdn2.microsoft.com/en-gb/library/ms670560.aspx
 (scroll to the message constants)

 This page seems to imply that the control can be queried with messages,
 however, my problem seems to be that pywin32.win32con does not define a
 constant for the LVM series of messages.



All the relevant message ids are in comCtl.h a 340k file. This might
explain why
win32con does only cover some ids. Best is to download and install the
platform sdk,
wich you may get for free from Microsoft. It comes shipped along with
all the headers
and the complete documentation for all the apis windows offers the
dedicated programmer.

http://www.microsoft.com/downloads/details.aspx?familyid=0BAF2B35-C656-4969-ACE8-E4C0C0716ADBdisplaylang=en


And ...just a hint, check the ctypes module, wich will give you full
access to all the
apis windows has to offer and lets you translate C code almost 1:1 to
python. 

Regards Jürgen

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Re: About alternatives to Matlab

[Carl Banks]

Jon Harrop wrote:
 Carl Banks wrote:
  0.56s C++ (direct arrays)
  0.61s F# (direct arrays)
  0.62s OCaml (direct arrays)
  1.38s OCaml (slices)
  2.38s Python (slices)
  10s Mathematica 5.1
  [snip]
  1.57s Python (in-place)
 
  So,
  optimized Python is roughly the same speed as naive Ocaml
  optimized Ocaml is roughly the same speed as C++

 Absolutely not:

 Optimized Python is 14% slower than badly written OCaml.

I'd call that roughly the same speed.  Did you use any sort of
benchmark suite that miminized testing error, or did you just run it
surrounded by calls to the system timer like I did?  If the latter,
then it's poor benchmark, and 10% accuracy is better than you can
expect.  (Naive tests like that tend to favor machine code.)

 Given the problem,
 rather than the Python solution, nobody would write OCaml code like that.

 Unoptimised but well-written OCaml/C/C++ is 2.5-2.8x faster than the fastest
 Python so far whilst also requiring about half as much code.

Frankly, I have a hard time believing anyone would naively write the
Ocaml code like the optimized version you posted.  You'd know better
than I, though.

 Optimising the C++ by hoisting the O(log n) temporary array allocations into
 one allocation makes it another 20% faster. I'm sure there are plenty more
 optimisations...

  There aren't any complicated types in the above code. In fact, there are
  only two types: float and float array.
 
  You're vastly underestimating the complexity of numpy objects.  They
  have an awful lot going on under the covers to make it look simple on
  the surface.  There's all kinds of type-checking and type-conversions.
  A JIT that folds loops together would have to have knowledge of that
  process, and it's a lot of knowledge to have.  That is not easy.

 My suggestion doesn't really have anything to do with numpy. If you had such
 a JIT you wouldn't use numpy in this case.

 That's my point, using numpy encouraged the programmer to optimise in the
 wrong direction in this case (to use slices instead of element-wise
 operations).

Ok, I can see that.  We have a sort of JIT compiler, psyco, that works
pretty well but I don't think it's as fast for large arrays as a good
numpy solution.  But it has more to deal with than a JIT for a
statically typed language.

  I was referring to the slicing specifically, nothing to do with
  functional programming. My F# and OCaml code are now basically identical
  to the C++ code.
 
  It is pretty strong thing to say that anything is fundamentally bad
  just because it's not fast as something else.  Fundamental badness
  ought to run deeper than some superficial, linear measure.

 The slice based approach is not only slower, it is longer, more obfuscated
 and more difficult to optimise. That doesn't just apply to Python and
 numpy, it also applies to Matlab, Mathematica etc.

 Which begs the question, if you were writing in a compiled language like F#
 would you ever use slices?

If I was writing in F#?  I absolutely would, because some problems are
most cleanly, readably, and maintainably done with slices.  I don't
have any speed-lust, and I don't waste time making things fast if they
don't need to be.  I would rather spend my time designing and
implementing the system, and optimizing things that actually need it.
I don't want to spend my time tracking down some stupid indexing error.

If it was critical for it to be fast, then I'd pull out the stops and
write it as efficiently as possible.  In my experience, a typical
middle size program will have half a dozen or so subroutines where it's
critical to be as fast as possible.

Will any other F# people do it?  I don't know if they all have
speed-lust, or if they'd all deliberately avoid slicing to prove some
kind of point about functional programming and/or non-machine-compiled
languages, but I assume there'd be some who would do it for the same
reasons I'd do it.

  Now, I was going to write the program in Python, and use the very
  convenient numpy to do the transformation part.

 What makes numpy convenient?

It's in Python, it's almost always fast enough, it's clean, it scales
up well, it expresses mathematical concepts straightforwardly, it's
well suppported, it has useful advanced functionality built in (linear
algebra, etc.).

And a lot of the time, you don't have to worry about indexing.

  No problem, numpy will be fast enough for my needs.

 Ok. But you'd rather have a compiler?

Python *is* compiled, buddy.  It has a VM that runs bytecode.

But, would I rather have a seperate compile to *machine code*, when an
automatic compile to VM code is fast enough?

Not remotely.  Compilers are a PITA and I avoid them when it's
possible.

  But wait!  It's silly try to optimize code in a fundamentally slow
  language!  It's vanity to even try!  I guess for the sake of getting
  this little D4 transform to double in speed

 C++ is currently 3.4x faster than Python.

Oh, well *that* made all the difference.


  I'll 

Re: evaluating gui modules, any experience on tkinter?

[[EMAIL PROTECTED]]

Tkinter is lame, but it works everywhere and is what I keep coming back
to despite my many complaints about it.

If youre application can be fit into a web porgramming framework, that
may well be the best way to go. Your browser can probably render a
better gui than any of the other frameworks can.

Cheers,
-T

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Re: About alternatives to Matlab

[Jon Harrop]

Carl Banks wrote:
 Optimized Python is 14% slower than badly written OCaml.
 
 I'd call that roughly the same speed.  Did you use any sort of
 benchmark suite that miminized testing error, or did you just run it
 surrounded by calls to the system timer like I did?

System timer, best of three.

 If the latter, 
 then it's poor benchmark, and 10% accuracy is better than you can
 expect.  (Naive tests like that tend to favor machine code.)

Yes, they are roughly the same speed. My objection was that this OCaml
program was not the unoptimised one, it was the badly written one. The
unoptimised OCaml/F#/C++ are all several times faster than this OCaml, and
much shorter and simpler too.

 Unoptimised but well-written OCaml/C/C++ is 2.5-2.8x faster than the
 fastest Python so far whilst also requiring about half as much code.
 
 Frankly, I have a hard time believing anyone would naively write the
 Ocaml code like the optimized version you posted.

That wasn't optimised. I haven't optimised any of my solutions. The OCaml I
posted was a naive convolution with some unnecessary allocation.

 You'd know better than I, though.

When asked to convolve an array with a 4-element array (h0..h3), I think
most programmers would write (pseudocode):

  for i in [0 .. n-4]
x[i] = h0 y[i] + h1 y[i+1] + h2 y[i+2] + h3 y[i+3]

in most languages. That is the essence of this benchmark.

You can express it even more succinctly with a dot product:

  for i in [0 .. n-4]
x[i] = h . y[i:]

In this case, you'd want a cyclic array type too.

 That's my point, using numpy encouraged the programmer to optimise in the
 wrong direction in this case (to use slices instead of element-wise
 operations).
 
 Ok, I can see that.  We have a sort of JIT compiler, psyco, that works
 pretty well but I don't think it's as fast for large arrays as a good
 numpy solution.  But it has more to deal with than a JIT for a
 statically typed language.

Ok. Perhaps starting a Python JIT in something like MetaOCaml or Lisp/Scheme
would be a good student project?

 Which begs the question, if you were writing in a compiled language like
 F# would you ever use slices?
 
 If I was writing in F#?  I absolutely would, because some problems are
 most cleanly, readably, and maintainably done with slices.  I don't
 have any speed-lust, and I don't waste time making things fast if they
 don't need to be.  I would rather spend my time designing and
 implementing the system, and optimizing things that actually need it.
 I don't want to spend my time tracking down some stupid indexing error.

Ok. Can you name some problems that are solved more easily with slices than
with indexing? I may have just answered my own question by posting some
really concise pseudocode that uses slices.

 Will any other F# people do it?  I don't know if they all have
 speed-lust, or if they'd all deliberately avoid slicing to prove some
 kind of point about functional programming and/or non-machine-compiled
 languages, but I assume there'd be some who would do it for the same
 reasons I'd do it.

My concern is that slices are being pulled into F# because they are popular
in languages like Python and Matlab but I've yet to see an example where
they are actually a good idea (in the context of F#, i.e. a compiled
language where indexing is as fast or faster).

 What makes numpy convenient?
 
 ...it scales up well...

What do you mean?

 ...it expresses mathematical concepts straightforwardly...

It didn't express this mathematical concept very straightforwardly.

 And a lot of the time, you don't have to worry about indexing.

Right. Ideally you want to factor that out without losing anything. Indeed,
if you do factor the C++ code you should get back to the underlying
mathematical definitions. Ideally, you'd want to write those directly and
have them executed efficiently.

  No problem, numpy will be fast enough for my needs.

 Ok. But you'd rather have a compiler?
 
 Python *is* compiled, buddy.  It has a VM that runs bytecode.

I meant a native-code compiler, of course.

 But, would I rather have a seperate compile to *machine code*, when an
 automatic compile to VM code is fast enough?
 
 Not remotely.  Compilers are a PITA and I avoid them when it's
 possible.

I can envisage a JIT Python compiler that would spot statically typed code,
compile it with no user intervention and then run it. I implemented such a
thing for Mathematica a few years ago.

 Why not drop to C for this one function?
 
 Why would I?  The assumptions clearly stated that numpy is fast enough.
  Why would I take several hours to write a C extension when I could do
 it with numpy in about 20 minutes, *and it's fast enough*?

Is it very difficult to interface Python to other languages efficiently?

 But let me offer you some advice: if you wan't to lure people from
 Python, speed isn't going to cut it.  Most people who chose Python
 (and, let's face it, most people who use Python chose it themselves)
 already knew it 

Python library for reading ODF Spreadsheets

[Jonathan Hunt]

Hi all,

I have had a look on google/freshmeat etc. so please forgive me if I've missed 
an obvious answer.

Can someone point me to a simple library to read/write ODF spreadsheets (i.e. 
OpenOffice Calc 2). I know I can interface with OOo but this is running on a 
server where I would rather avoid a full-on library. 

Something like 
http://sourceforge.net/projects/pyexcelerator/
but for reading ODF.

I have found write only solutions - but no read library except for the full 
Monte OOo/UNO which I want to avoid.

Please, please help. Or the pragmatist in me will be forced to use XLS to get 
this job done. Thanks in advance for any help.

Jonny

(I'm not on the list. Please CC me answers).
-- 
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Website: http://www.me.net.nz (PGP Public Key available there)
Ph: +6463535975 Mob: +64212106185 Work: +6463505799x3529
He is no fool who gives what he cannot keep to gain what he cannot lose.
Jim Elliot


pgpF114vbyRQI.pgp
Description: PGP signature
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Re: Python library for reading ODF Spreadsheets

[John Machin]

On 4/12/2006 10:18 AM, Jonathan Hunt wrote:
 Hi all,
 
 I have had a look on google/freshmeat etc. so please forgive me if I've 
 missed 
 an obvious answer.
 
 Can someone point me to a simple library to read/write ODF spreadsheets (i.e. 
 OpenOffice Calc 2). I know I can interface with OOo but this is running on a 
 server where I would rather avoid a full-on library. 
 
 Something like 
 http://sourceforge.net/projects/pyexcelerator/
 but for reading ODF.
 
 I have found write only solutions - but no read library except for the full 
 Monte OOo/UNO which I want to avoid.
 
 Please, please help. Or the pragmatist in me will be forced to use XLS to get 
 this job done. Thanks in advance for any help.

There is no such library as you describe.

 
 Jonny
 
 (I'm not on the list. Please CC me answers).

Such a request is usually considered to be impertinent bludging and is 
likely to get you *no* answers. Consider subscribing to the list and 
reading it. Alternatively you could use a newsreader pointed at 
news:comp.lang.python or a browser pointed at 
http://groups.google.com/group/comp.lang.python.

HTH,
John



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Re: ftputil upload error

[Mark]

On Sat, 02 Dec 2006 04:03:53 -0800, Croteam wrote:

 FTPIOError: 550 popravak.txt: Access is denied.

Seems pretty self-explanatory to me.

M
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Why not just show the out-of-range index?

[Russ]

Every Python programmer gets this message occasionally:

IndexError: list index out of range

The message tells you where the error occurred, but it doesn't tell you
what the range and the offending index are. Why does it force you to
determine that information for yourself when it could save you a step
and just tell you? This seems like a no-brainer to me. Am I missing
something?

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Re: Why not just show the out-of-range index?

[James Stroud]

Russ wrote:
 Every Python programmer gets this message occasionally:
 
 IndexError: list index out of range
 
 The message tells you where the error occurred, but it doesn't tell you
 what the range and the offending index are. Why does it force you to
 determine that information for yourself when it could save you a step
 and just tell you? This seems like a no-brainer to me. Am I missing
 something?
 

I think you have a point. I am curious to see how far people are willing 
to go to defend this omission. It promises to be entertaining.

James

-- 
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UCLA-DOE Institute for Genomics and Proteomics
Box 951570
Los Angeles, CA 90095

http://www.jamesstroud.com/
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Re: Why not just show the out-of-range index?

[John Machin]

James Stroud wrote:
 Russ wrote:
  Every Python programmer gets this message occasionally:
 
  IndexError: list index out of range
 
  The message tells you where the error occurred, but it doesn't tell you
  what the range and the offending index are. Why does it force you to
  determine that information for yourself when it could save you a step
  and just tell you? This seems like a no-brainer to me. Am I missing
  something?
 

 I think you have a point. I am curious to see how far people are willing
 to go to defend this omission. It promises to be entertaining.
 

Add Syntax Error: invalid syntax to the list ...

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Re: Why not just show the out-of-range index?

[Robert Kern]

James Stroud wrote:
 Russ wrote:
 Every Python programmer gets this message occasionally:

 IndexError: list index out of range

 The message tells you where the error occurred, but it doesn't tell you
 what the range and the offending index are. Why does it force you to
 determine that information for yourself when it could save you a step
 and just tell you? This seems like a no-brainer to me. Am I missing
 something?
 
 I think you have a point. I am curious to see how far people are willing 
 to go to defend this omission. It promises to be entertaining.

I'm not sure that anybody is going to defend it as a deliberate omission.
Rather, they (like I) will encourage to OP to submit a patch that fixes the 
problem.

-- 
Robert Kern

I have come to believe that the whole world is an enigma, a harmless enigma
 that is made terrible by our own mad attempt to interpret it as though it had
 an underlying truth.
  -- Umberto Eco

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Re: Parsing data from pyserial

[Si Ballenger]

On Sun, 03 Dec 2006 18:44:07 -, Grant Edwards
[EMAIL PROTECTED] wrote:

On 2006-12-03, Si Ballenger [EMAIL PROTECTED] wrote:

 In my dealing with serial gizmos I have to put a delay between
 the request sent to the gizmo and the reading of the serial input
 buffer for returned data. Serial ports and gizmos need some time
 to do their thing.

I doubt that's the issue.  He's reading with a 1-second timeout
value.

 I would think a time delay would be needed between the below two
 lines in the code if he expects to get a useable data string back
 from the gizmo for the command sent to it. 

   ser.write(TC 016 240 100 240 016 240\r\n)
   reading = ser.read(40)

No. A delay isn't needed as long as the device responds within
1 second.  The read() call will wait up to 1 second for the
first byte of the response.

Per what was posted (below), it appears that the the appropriate
data is being received. It may be possible that the cam may be
sending in a mode that is not in alignment with the binary
transmission mode of the serial port. As a test I'd jumper
between the Tx and Rx pin on the serial port and then send out
the M line being received, then see if it will parse as
expected.  

Here is an example output: 

M 37 79 3 4 59 124 86 25
['59', '123', '87', '25', 'M', '37', '79', '3', '4', '59',
'124', '86', '25', 'M
']
M 38 77 3 2 59 124 86 25
['39', '85', '26', 'M', '38', '77', '3', '2', '59', '124', '86',
'25', 'M', '38'
, '7']
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Re: How to realize the interactive python in Eclipse?

[Ravi Teja]

purple wrote:
 I have installed the Eclipse and the plug-in Pydev. Also, I have add an
 python program in the external tools. When I run the python program in
 the external tools, i can type python command just like in the python
 shell.But when I finished running a python file, in the console, I
 could not type any command to check some argument generated in the
 process. Is there any way I can make it?
 thank you~~

I am beginning to wonder if you attempting to use PyDev as nothing more
than a programmer's editor. PyDev is a lot more. You need not debug
this way since it includes a visual debugger. Be sure to read the
documentation at the web site.

http://pydev.sourceforge.net/debug.html
http://pydev.sourceforge.net/faq.html

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Re: Why not just show the out-of-range index?

[Russ]

 Rather, they (like I) will encourage to OP to submit a patch that fixes the 
 problem.

Now, that would be rather silly. I would have to familiarize myself
with the code for the Python interpreter, then send a patch to the
maintainers (and hope they notice it in their inboxes), while the
maintainers themselves could probably fix the problem in two minutes
flat. No thanks!

My suggestion is trivial to implement and would benefit every Python
programmer (even if only slightly), so I don't think it is too much to
ask for.

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Re: problem formatting dates from text fields.

[krishnakant Mane]

On 04/12/06, Dennis Lee Bieber [EMAIL PROTECTED] wrote:
   You don't show us what format is used in the database, so there is
 nothing to base a conversion on. Is it year/month/day, month/day/year;
 months numeric or alpha (abbreviated or spelled out). Fields separated
 by space, comma, -, :, or /


the format in the text field is dd/mm/ which is perfect for what I need.
but the problem as I said is to get this text into a value that can
fit into a date time picker.
can this be done?
Krishnakant.
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Re: Parsing data from pyserial

[John Machin]

Si Ballenger wrote:

 Per what was posted (below), it appears that the the appropriate
 data is being received.
[snip]

 Here is an example output:

 M 37 79 3 4 59 124 86 25
 ['59', '123', '87', '25', 'M', '37', '79', '3', '4', '59',
 '124', '86', '25', 'M
 ']
 M 38 77 3 2 59 124 86 25
 ['39', '85', '26', 'M', '38', '77', '3', '2', '59', '124', '86',
 '25', 'M', '38'
 , '7']

Based on the split() results (presumably much more reliable than the
print reading results)  what appears to me is:
fragment '59', '123', '87', '25'
packet 'M', '37', '79', '3', '4', '59', '124', '86', '25'
fragment 'M',  '39' [see note]
fragment '85', '26'
packet 'M', '38', '77', '3', '2', '59', '124', '86', '25',
fragment 'M', '38'

[note] the 39 obviously aligns with the 37 and 38s, not with the 123
and 124s. However the boundary of the 2 split() results lies before the
39, not after. Puzzling.

In any case, I wouldn't call that the appropriate data is being
received -- looks like chunks missing to me.

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trouble with matplotlib

[lisa . engblom]

Hi,

I am using matplotlib with python to generate a bunch of charts.  My
code works fine for a single iteration, which creates and saves 4
different charts.  The trouble is that when I try to run it for the
entire set (about 200 items) it can run for 12 items at a time.  On the
13th, I get an error from matplotlib that says it can't access data.
However, if I start the program at the point it failed before it works
fine and will create the charts for the next 12 before failing.  I
assume that I am not closing the files properly somehow or otherwise
misallocating memory.  This is the function that creates a chart:

#create and save the figure
def CreateFigure(state, facility, unit, SO2, increment, year, P99):
size = len(SO2)

#Create Plot
figure(1, figsize=(10,8))
bar(range(1, size+2), SO2, width=0.1, color='k')
grid(True)
xlim(0,size)
ylim(0, 1.1*SO2[-1])
ylabel('SO2 [lb/hr]')
heading = ConstructFigName(state, facility, unit, increment, year)
title(heading)

#set handles
xticklines = getp(gca(), 'xticklines')
xgridlines = getp(gca(), 'xgridlines')
xticklabels = getp(gca(), 'xticklabels')
yticklines = getp(gca(), 'yticklines')

#set properties
setp(xticklines, visible=False)
setp(xgridlines, visible=False)
setp(xticklabels, visible=False)
setp(yticklines, visible=False)

axhspan(P99, P99, lw=3, ec='r', fc='r')
ax = gca()
#P99 = str(P99)
P99 = '%0.1f' % P99
text(0.01, 0.95, '99th Percentile: '+P99+' lb/hr',
transform=ax.transAxes)

figpath = ConstructFigPath(state, facility, unit, increment, year)
savefig(figpath)
close()


Can you see the problem?

thanks,
-Lisa

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Re: Joining data from three different files to be written into three Columns

[Dawn Abbott]

Everything works in my program except for when it prints out the number is
surrounded by brackets but I need to print the number without the brackets.
Does anyone know an easy way to do this?
#!/usr/bin/env python
import array
fin = open('relative_x.INT32','rb')
fin1=open('relative_y.INT32','rb')
fin2=open('income.INT32','rb')
outfile=open('test.txt','w')

data=[]
data1=[]
data2=[]
while True:
   try:
   myInts=array.array('l')
   myInts.fromfile(fin,1)
   data.append(myInts.tolist())
   myInts1=array.array('l')
   myInts1.fromfile(fin1,1)
   data1.append(myInts1.tolist())
   myInts2=array.array('l')
   myInts2.fromfile(fin2,1)
   data2.append(myInts2.tolist())
   data3=zip(data,data1,data2)
   except EOFError:
   break

   for record in data:
   print record[0],record[1],record[2]



thanks
Dawn
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Re: How to realize the interactive python in Eclipse?

[purple]

Thank you for your website. I used to work with the python shell, but
it is quite boring in managing the files, so I know the eclipse and
pydev. I think I should focus on the documentations first. Thank you
very much.


 I am beginning to wonder if you attempting to use PyDev as nothing more
 than a programmer's editor. PyDev is a lot more. You need not debug
 this way since it includes a visual debugger. Be sure to read the
 documentation at the web site.

 http://pydev.sourceforge.net/debug.html
 http://pydev.sourceforge.net/faq.html

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Re: Why not just show the out-of-range index?

[[EMAIL PROTECTED]]

John Machin wrote:
 James Stroud wrote:
  Russ wrote:
   Every Python programmer gets this message occasionally:
  
   IndexError: list index out of range
  
   The message tells you where the error occurred, but it doesn't tell you
   what the range and the offending index are. Why does it force you to
   determine that information for yourself when it could save you a step
   and just tell you? This seems like a no-brainer to me. Am I missing
   something?
  
 
  I think you have a point. I am curious to see how far people are willing
  to go to defend this omission. It promises to be entertaining.
 

 Add Syntax Error: invalid syntax to the list ...

But at least if you're using IDLE, the point of syntax error
is highlighted.

When I was a programmer, I thought as a programmer,
I spake as a programmer and I understood as a programmer.
But when I became a User, I put away such childish things.

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Parsing data from pyserial, an (inefficient) solution

[Lone Wolf]

I want to thank everybody who tried to help me, and also to post
my solution, even though I don’t think it is a very good one.

Many of you correctly guessed that there was an “\r” included
with the packet from the CUMcam, and you were correct. The
actual format of the packet is: M xxx xxx xxx xxx xxx xxx
xxx xxx\r. Unfortunately, splitting the packet using \r wouldn’t
help because the format of the data stream that I get with the
components variable (after I split the reading file according to
“M”) generally doesn’t include a complete packet at first. For
example, I get:  [xxx xxx xxx\r, yyy yyy yyy yyy yyy yyy yyy
yyy/r,  zzz zzz zzz]  Therefore, data from before the
first \r  (which I have shown as xxx) generally is incomplete
and I need to go on to the second packet. 

Also, for those of you who suggested some kind of delay before
reading the serial port, you were right. The first packet from
the CMUcam is always a null. 

Anyway, here is my code:



# This program reads a serial port hookup up to a CMUcam version
1.
# It tracks the middle of a green object and provides a
confidence estimate

import serial

ser=serial.Serial('com1',baudrate=115200, bytesize=8,
parity='N', stopbits=1,xonxoff=0, timeout=1)

ser.write(TC 016 240 100 240 016 240\r\n)  #This line orders
the CMUcam to track green
reading = ser.read(40)  # CMUcam's first data packet is null, so
this line gets it out of the way

for i in range(0,100,1):
reading = ser.read(40)
components = reading.split(M)
components = components[1]
if len(components)  23:  # If shorter than 24 it won't have
enough data for a full packet
subcomponents = components.split()
mx = int(subcomponents[0])
my = int(subcomponents[1])
confidence = int(subcomponents[7])
print mx, my, confidence 
ser.close


The really sad thing is that I get a perfectly constructed
packet from the reading variable, and that gets butchered when I
try to slice it up to pick out individual elements. Since
pyserial doesn’t do anything to rearrange the data, then the
CMUcam must do the heavy lifting of extracting a perfect packet
from the data stream. It’s a real shame I couldn’t use it
because the program would be more efficient. FWIW, this code
will analyze 2-3 frames per second on my computer, which is
enough for my purposes.

In case you couldn’t tell from the questions/code, I am a total
beginner, and I really appreciate this list. All I needed was a
hand, not a handout. Wolves are willing to hunt for their
supper.



Get your own 800 number
Voicemail, fax, email, and a lot more
http://www.ureach.com/reg/tag
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Re: trouble with matplotlib

[[EMAIL PROTECTED]]

One hack could be to reload the module on each pass.

Cheers,
-T

[EMAIL PROTECTED] wrote:
 Hi,

 I am using matplotlib with python to generate a bunch of charts.  My
 code works fine for a single iteration, which creates and saves 4
 different charts.  The trouble is that when I try to run it for the
 entire set (about 200 items) it can run for 12 items at a time.  On the
 13th, I get an error from matplotlib that says it can't access data.
 However, if I start the program at the point it failed before it works
 fine and will create the charts for the next 12 before failing.  I
 assume that I am not closing the files properly somehow or otherwise
 misallocating memory.  This is the function that creates a chart:

 #create and save the figure
 def CreateFigure(state, facility, unit, SO2, increment, year, P99):
 size = len(SO2)

 #Create Plot
 figure(1, figsize=(10,8))
 bar(range(1, size+2), SO2, width=0.1, color='k')
 grid(True)
 xlim(0,size)
 ylim(0, 1.1*SO2[-1])
 ylabel('SO2 [lb/hr]')
 heading = ConstructFigName(state, facility, unit, increment, year)
 title(heading)

 #set handles
 xticklines = getp(gca(), 'xticklines')
 xgridlines = getp(gca(), 'xgridlines')
 xticklabels = getp(gca(), 'xticklabels')
 yticklines = getp(gca(), 'yticklines')

 #set properties
 setp(xticklines, visible=False)
 setp(xgridlines, visible=False)
 setp(xticklabels, visible=False)
 setp(yticklines, visible=False)

 axhspan(P99, P99, lw=3, ec='r', fc='r')
 ax = gca()
 #P99 = str(P99)
 P99 = '%0.1f' % P99
 text(0.01, 0.95, '99th Percentile: '+P99+' lb/hr',
 transform=ax.transAxes)

 figpath = ConstructFigPath(state, facility, unit, increment, year)
 savefig(figpath)
 close()
 
 
 Can you see the problem?
 
 thanks,
 -Lisa

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Re: Why not just show the out-of-range index?

[John Machin]

[EMAIL PROTECTED] wrote:
 John Machin wrote:
  Add Syntax Error: invalid syntax to the list ...

 But at least if you're using IDLE, the point of syntax error
 is highlighted.


Same when using the interactive interpreter, the point of syntax error
is highlighted with a caret. However the highlighting of WHERE is
useless to people who don't have a clue WHAT the error is, and it needs
a forensic guru to suss it out as for example Peter Otten did, only
yesterday:

Are you perhaps mixing tabs and spaces?

 def f():

... print hello # four spaces before 'print'
... return 42 # one tab before 'return'
  File stdin, line 3
return 42
^
SyntaxError: invalid syntax 


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Re: Why not just show the out-of-range index?

[Robert Kern]

Russ wrote:
 Rather, they (like I) will encourage to OP to submit a patch that fixes the 
 problem.
 
 Now, that would be rather silly. I would have to familiarize myself
 with the code for the Python interpreter, then send a patch to the
 maintainers (and hope they notice it in their inboxes), while the
 maintainers themselves could probably fix the problem in two minutes
 flat. No thanks!

And I believe that answers your original question.

PS: begging for a fix on comp.lang.python is even less likely to get the
developer's attention than posting a patch. They listen to patch submissions
much more than comp.lang.python. At the very least, you should submit a bug
report even if you don't want to take the opportunity to learn how to fix it
yourself.

-- 
Robert Kern

I have come to believe that the whole world is an enigma, a harmless enigma
 that is made terrible by our own mad attempt to interpret it as though it had
 an underlying truth.
  -- Umberto Eco

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Re: Parsing data from pyserial

[Si Ballenger]

On 3 Dec 2006 17:33:59 -0800, John Machin
[EMAIL PROTECTED] wrote:

In any case, I wouldn't call that the appropriate data is being
received -- looks like chunks missing to me.

Well, below is the posted expected return data format from the
cam and below that is what has been reported to be returned from
the cam when it is polled, which appears to be a fairly
reasonable match. I assume that each xxx is a decimal number
repersenting a single byte. In the binary mode each x in the
string might be considered a byte in itelf and possibly evaluated
as such. Anyhow it should be easy to see if the received string
can be parsed on it own correctly when not being received via the
serial port. That would start to narrow down where something not
understood is comming into play.

M xxx xxx xxx xxx xxx xxx xxx xxx
M 37 79 3 4 59 124 86 25


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ANN: UliPad 3.6 released!

[limodou]

What's it?


It's an Editor based on wxPython. UliPad(NewEdit is the old name) uses
Mixin and Plugin technique as its architecture. Most of its classes
can be extended via mixin and plugin
components, and finally become an integrity class at
creating the instance. So UliPad is very dynamic. You can write the
new features in new files, and hardly need to modify the existing
code. And if you want to extend the existing classes, you could write
mixins and plugins, and this will be bound to the target class that I
call Slot Class. This technique will make the changes centralized
and easily managed.

What's new in 3.6
==

New features and improvement:

#. Improve definition jump, and if there is no ctag file exist, UliPad
can jump in one source file, including: variable, class, method, etc
#. Improve auto-completion: variable auto-detect, class structure
detect, base class recognize, etc. And it can improve your typing. As
you backspace something, auto-completion will also available. And you
can also write parameter datatype in function docstring, UliPad will
auto recognize the parameter datatype.
#. Add range support for live regular expression search support
#. Add pairprog plugin, it's a collaborative programming support. One
instance can be a server, and others can be client. For server, you
can share source file with all client, and both server and client can
change the same document and move the caret. UliPad support
multi-client. And it has a chatroom support, so developer can use it
to talk with each other.
#. Add fortran, and lua syntax support. For fortran you should enable
fortran plugin.
#. Improve the display structure and content of class browser
#. Add css auto-completion support

Changes:

#. Improve class browser windown, and single-click on class icon will
expand or collapse the children items
#. Fix the bug of clicking on Cancel button on Python Parameter Input
Dialog still running
#. Fix reStructuredText syntax highlight processing bug
#. Fix python syntax analysis bug
#. Fix cann't restore the last directories entries as reopen the
directory browser bug
#. Fix if the filename or directory that you want to open command line
window on it(on windows platform) is not the same hard driver, will
open wrong path bug.
#. Fix music plugin's bug
#. Remove open recently-directory functionality
#. Fix as changing the encode of the document, but the tab page title
doesn't be changed bug


Where to download it?


download lastest version 3.6:
http://wiki.woodpecker.org.cn/moin/UliPad?action=AttachFiledo=gettarget=ulipad_3.6.zip
also have windows installer:
http://wiki.woodpecker.org.cn/moin/UliPad?action=AttachFiledo=gettarget=UliPad.3.6.exe
wiki: http://wiki.woodpecker.org.cn/moin/UliPad
svn: http://cvs.woodpecker.org.cn/svn/woodpecker/ulipad/trunk
maillist: http://groups.google.com/group/ulipad

If you have any problem as using UliPad, welcome to join the UliPad
maillist to discuss.

Hope you enjoy it. ;-)

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UliPad The Python Editor: http://wiki.woodpecker.org.cn/moin/UliPad
My Blog: http://www.donews.net/limodou
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Re: Why not just show the out-of-range index?

[[EMAIL PROTECTED]]

John Machin wrote:
 [EMAIL PROTECTED] wrote:
  John Machin wrote:
   Add Syntax Error: invalid syntax to the list ...
 
  But at least if you're using IDLE, the point of syntax error
  is highlighted.
 

 Same when using the interactive interpreter, the point of syntax error
 is highlighted with a caret. However the highlighting of WHERE is
 useless to people who don't have a clue WHAT the error is, and it needs
 a forensic guru to suss it out as for example Peter Otten did, only
 yesterday:
 
 Are you perhaps mixing tabs and spaces?

  def f():

 ... print hello # four spaces before 'print'
 ... return 42 # one tab before 'return'
   File stdin, line 3
 return 42
 ^
 SyntaxError: invalid syntax
 

Well, more information would be better, but at least it's
not as bad as Windows:

   Application xxx could not be started because a
   required file could not be found. I know the name
   of the file but I am not going to tell you what
   it is.

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Re: Parsing data from pyserial, an (inefficient) solution

[John Machin]

Lone Wolf wrote:

Your code has a problem when the first character of reading is 'M': you
will miss the full packet and pick up a fragment. The length test that
you are doing to reject the fragment is a kludge. If the average length
of a packet is say 25, then you are throwing away 4% of all packets on
average. Try this [untested]:

reading = ser.read(40)
# components = reading.split(M)
# components = components[1]
# if len(components)  23:  # If shorter than 24 it won't have
enough data for a full packet
 # subcomponents = components.split()
 pos_past_m = reading.index('M') + 1
 subcomponents = reading[pos_past_m:].split()
 mx = int(subcomponents[0])
 my = int(subcomponents[1])
 confidence = int(subcomponents[7])
 print mx, my, confidence


 The really sad thing is that I get a perfectly constructed
 packet from the reading variable,

What we tell you three times is true, you are *NOT* getting a perfectly
formed packet from the reading variable; you are getting 40 bytes of
guff which will be long enough to contain a packet with possible stray
fragments at either end.

Do this:
print len(reading)
print repr(reading)
and see for yourself.

  and that gets butchered when I
 try to slice it up to pick out individual elements. Since
 pyserial doesn't do anything to rearrange the data, then the
 CMUcam must do the heavy lifting of extracting a perfect packet
 from the data stream.

Huh? I thought the CMUcam was *creating* the data stream -- how could
it be *extracting* a perfect packet from it?

 It's a real shame I couldn't use it
 because the program would be more efficient.

Somebody else gave you a clue: use the readline method instead of the
read method; have you tried that? It's more likely to stop on a packet
boundary that what you are doing.

As far as starting on a packet boundary is concerned, have you explored
your options with buffering and flow control?

 FWIW, this code
 will analyze 2-3 frames per second on my computer, which is
 enough for my purposes.

 In case you couldn't tell from the questions/code, I am a total
 beginner, and I really appreciate this list. All I needed was a
 hand, not a handout. Wolves are willing to hunt for their
 supper.

Independence is one thing. Ignoring plausible truth told to you by
multiple independent people with no axe to grind is another :-)

HTH,
John

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Re: About alternatives to Matlab

[George Sakkis]

Jon Harrop wrote:

 Ok. Perhaps starting a Python JIT in something like MetaOCaml or Lisp/Scheme
 would be a good student project?

I guess for a student project it's not that important, but if you have
higher ambitions, make sure you read
http://dirtsimple.org/2005/10/children-of-lesser-python.html before you
commit to writing what will turn out to be yet another 80% Python VM
/ JIT compiler.

George

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Re: Parsing data from pyserial

[John Machin]

Si Ballenger wrote:
 On 3 Dec 2006 17:33:59 -0800, John Machin
 [EMAIL PROTECTED] wrote:

 In any case, I wouldn't call that the appropriate data is being
 received -- looks like chunks missing to me.

 Well, below is the posted expected return data format from the
 cam and below that is what has been reported to be returned from
 the cam when it is polled, which appears to be a fairly
 reasonable match. I assume that each xxx is a decimal number
 repersenting a single byte. In the binary mode each x in the
 string might be considered a byte in itelf and possibly evaluated
 as such. Anyhow it should be easy to see if the received string
 can be parsed on it own correctly when not being received via the
 serial port. That would start to narrow down where something not
 understood is comming into play.

 M xxx xxx xxx xxx xxx xxx xxx xxx
 M 37 79 3 4 59 124 86 25

Try reading previous posts. The OP reported that to be returned from
the cam, based on print forty_bytes, not print repr(forty_bytes). I
think everybody (including possibly even the OP) is willing to believe
that the cam is *generating* correct parseable stuff, followed by '\r'
-- the problem now is how to get as many samples per second as is
reasonable in the face of problems like lack of buffering, flow
control, etc.

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Re: Why not just show the out-of-range index?

[Jean-Paul Calderone]

On 3 Dec 2006 17:23:49 -0800, Russ [EMAIL PROTECTED] wrote:

 Rather, they (like I) will encourage to OP to submit a patch that fixes the 
 problem.

Now, that would be rather silly. I would have to familiarize myself
with the code for the Python interpreter, then send a patch to the
maintainers (and hope they notice it in their inboxes), while the
maintainers themselves could probably fix the problem in two minutes
flat. No thanks!

And I have some laundry that I would like you to do for me.  Let me know
when a convenient time for you to pick it up would be.

Jean-Paul
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Re: Python library for reading ODF Spreadsheets

[[EMAIL PROTECTED]]

ODT is an XML format, so you can use any XML library, including the one
in the default python distribution. It might be zipped XML in which
case you will need to uncompress it first.

-T


John Machin wrote:
 On 4/12/2006 10:18 AM, Jonathan Hunt wrote:
  Hi all,
 
  I have had a look on google/freshmeat etc. so please forgive me if I've 
  missed
  an obvious answer.
 
  Can someone point me to a simple library to read/write ODF spreadsheets 
  (i.e.
  OpenOffice Calc 2). I know I can interface with OOo but this is running on a
  server where I would rather avoid a full-on library.
 
  Something like
  http://sourceforge.net/projects/pyexcelerator/
  but for reading ODF.
 
  I have found write only solutions - but no read library except for the full
  Monte OOo/UNO which I want to avoid.
 
  Please, please help. Or the pragmatist in me will be forced to use XLS to 
  get
  this job done. Thanks in advance for any help.

 There is no such library as you describe.

 
  Jonny
 
  (I'm not on the list. Please CC me answers).

 Such a request is usually considered to be impertinent bludging and is
 likely to get you *no* answers. Consider subscribing to the list and
 reading it. Alternatively you could use a newsreader pointed at
 news:comp.lang.python or a browser pointed at
 http://groups.google.com/group/comp.lang.python.
 
 HTH,
 John

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Re: Why not just show the out-of-range index?

[Russ]

Jean-Paul Calderone wrote:

 And I have some laundry that I would like you to do for me.  Let me know
 when a convenient time for you to pick it up would be.

What that has to do with this thread escapes me, but since you
apparently have nothing better to do than track down information that
should have been provided to you, it's no wonder you don't have enough
time to do your own laundry.

When you call information to get a phone number, do you first ask if
they have the number, then call back a second time to get it if the
answer is yes?

If a policemen gives you a speeding ticket, do you expect him to tell
you how fast he thinks you were going, or are you content to wait for
the court date?

Get your mother to do your laundry -- after she dresses you in the
morning.

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Re: Why not just show the out-of-range index?

[Gary Herron]

Russ wrote:
 Rather, they (like I) will encourage to OP to submit a patch that fixes the 
 problem.
 

 Now, that would be rather silly. I would have to familiarize myself
 with the code for the Python interpreter, then send a patch to the
 maintainers (and hope they notice it in their inboxes), while the
 maintainers themselves could probably fix the problem in two minutes
 flat. No thanks!

 My suggestion is trivial to implement and would benefit every Python
 programmer (even if only slightly), so I don't think it is too much to
 ask for.

   
But with that argument you just perpetuate the problem. It is the way it 
is because nobody has cared enough to make it different. That error 
message has certainly never bothered me enough to wish for something 
different.

You may be able to prompt someone into changing it, but if we've gone 
this long without caring to fix it, then I'd not hold out much hope for 
that. Python and the whole open source movement is a volunteer effort by 
people who care enough to contribute. Your contributions would be 
welcome, but your complaints are likely to be ignored.

Gary Herron

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Re: problem formatting dates from text fields.

[krishnakant Mane]

is there a soft copy of wxpython in action available for free download?
I saw the book on my book store but since I am totally blind, I have
to depend on soft copies.
Krishnakant.
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class property methods getting called only once

[[EMAIL PROTECTED]]

In the following code, I could not find out why the set and get methods
are not called once I set the property.


 class Test:
... def __init__(self):
... self._color = 12
... def _setcolor(self,value):
... print 'setting'
... self._color = value
... def _getcolor(self):
... print 'getting'
... return self._color
... color = property(_getcolor,_setcolor)
...
 a = Test()
 a.color
getting
12
 a.color = 22
 a.color
22

For some reason the set method is not getting called at all, Anybody
has any clue?

thanks.
--
Suresh

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Re: Why not just show the out-of-range index?

[John Machin]

Jean-Paul Calderone wrote:
 On 3 Dec 2006 17:23:49 -0800, Russ [EMAIL PROTECTED] wrote:
 
  Rather, they (like I) will encourage to OP to submit a patch that fixes 
  the problem.
 
 Now, that would be rather silly. I would have to familiarize myself
 with the code for the Python interpreter, then send a patch to the
 maintainers (and hope they notice it in their inboxes), while the
 maintainers themselves could probably fix the problem in two minutes
 flat. No thanks!

 And I have some laundry that I would like you to do for me.  Let me know
 when a convenient time for you to pick it up would be.

 Jean-Paul

Perhaps a better analogy is that the OP has observed (correctly IMHO)
that the robes of *all* Pythonistas, including those not yet born and
those not yet converted from heathen languages, could be whiter than
what they are. There are others whose capability to implement an
enhancement is likely to be much greater than his.

IOW, apart from being somewhat impolite, he may:
* not be able to write C
* not understand that apart from listobject.c, he might have to patch
(OTTOMH) stringobject.c, tupleobject.c, arraymodule.c and who knows
what else [see below]
* not come up with a good message

Would the following be acceptable, BTW?

|  [4, 5, 6][10]
| IndexError: list index 10 out of range(3)
|  [4, 5, 6][-4]
| IndexError: list index -4 out of range(3)

or would something like
 ... out of range; len is 3
be better?

Footnote: Based on 2.4.3 source, quite a few files, many with multiple
lines to patch:

C:\Python_source\Python-2.4.3\Objectsgrep -n index out of range *.c
File bufferobject.c:
406 PyErr_SetString(PyExc_IndexError, buffer index
out of range);
450 buffer assignment index out of
range);
File listobject.c:
144 list index out of range);
165 list assignment index out of
range);
389 list index out of range);
693 list assignment index out of
range);
881 PyErr_SetString(PyExc_IndexError, pop index
out of range);
File rangeobject.c:
143 xrange object index out of
range);
File stringobject.c:
1041PyErr_SetString(PyExc_IndexError, string index
out of range);
File structseq.c:
62  PyErr_SetString(PyExc_IndexError, tuple index
out of range);
File tupleobject.c:
104 PyErr_SetString(PyExc_IndexError, tuple index
out of range);
123 tuple assignment index out of
range);
310 PyErr_SetString(PyExc_IndexError, tuple index
out of range);
File unicodeobject.c:
5241PyErr_SetString(PyExc_IndexError, string index out of
range);

C:\Python_source\Python-2.4.3\Modulesgrep -n index out of range *.c
File arraymodule.c:
599 PyErr_SetString(PyExc_IndexError, array index
out of range);
767  array assignment index out of
range);
997 PyErr_SetString(PyExc_IndexError, pop index
out of range);
File collectionsmodule.c:
399 deque index out of range);
461 deque index out of range);
File mmapmodule.c:
648 PyErr_SetString(PyExc_IndexError, mmap index
out of range);
736 PyErr_SetString(PyExc_IndexError, mmap index
out of range);
File regexmodule.c:
181 PyErr_SetString(RegexError, group() index out
of range);
File _heapqmodule.c:
19  PyErr_SetString(PyExc_IndexError, index out of
range);
58  PyErr_SetString(PyExc_IndexError, index out of
range);
136 PyErr_SetString(PyExc_IndexError, index out of
range);
173 PyErr_SetString(PyExc_IndexError, index out of
range);
310 PyErr_SetString(PyExc_IndexError, index out of
range);
349 PyErr_SetString(PyExc_IndexError, index out of
range);

Cheers,
John

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Re: problem formatting dates from text fields.

[Robert Kern]

krishnakant Mane wrote:
 is there a soft copy of wxpython in action available for free download?
 I saw the book on my book store but since I am totally blind, I have
 to depend on soft copies.

It is not available for free, no. However, it is available in PDF form from
Manning's website:

  http://www.manning.com/rappin/

If their Yahoo store is not accessible via your web reader (I have no
experience, so I won't depend on it), you can email the publisher's customer
service at [EMAIL PROTECTED] and I'm sure they will get the book to you in a
form you can read.

-- 
Robert Kern

I have come to believe that the whole world is an enigma, a harmless enigma
 that is made terrible by our own mad attempt to interpret it as though it had
 an underlying truth.
  -- Umberto Eco

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Re: class property methods getting called only once

[limodou]

On 3 Dec 2006 21:24:03 -0800, [EMAIL PROTECTED]
[EMAIL PROTECTED] wrote:
 In the following code, I could not find out why the set and get methods
 are not called once I set the property.


  class Test:
 ... def __init__(self):
 ... self._color = 12
 ... def _setcolor(self,value):
 ... print 'setting'
 ... self._color = value
 ... def _getcolor(self):
 ... print 'getting'
 ... return self._color
 ... color = property(_getcolor,_setcolor)
 ...
  a = Test()
  a.color
 getting
 12
  a.color = 22
  a.color
 22

 For some reason the set method is not getting called at all, Anybody
 has any clue?

 thanks.

property can only be used in New Style Class. So you should write your Test as:

class Test(object):

And try again.

-- 
I like python!
UliPad The Python Editor: http://wiki.woodpecker.org.cn/moin/UliPad
My Blog: http://www.donews.net/limodou
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Re: Why not just show the out-of-range index?

[Russ]

John Machin wrote:

 Perhaps a better analogy is that the OP has observed (correctly IMHO)
 that the robes of *all* Pythonistas, including those not yet born and
 those not yet converted from heathen languages, could be whiter than
 what they are. There are others whose capability to implement an
 enhancement is likely to be much greater than his.

I love Python, but every time I get an out-of-range error message, I
wonder why it didn't just tell me what the out-of-range index was and
what the allowable range was. Certainly that information must be
available to the exception handler, or how would it know that it is out
of range? And no, it's not a big deal, maybe it's even trivial, but
after about the 100th time I finally decided to suggest that it be
fixed. I started with comp.lang.python because I had no idea whether
this issue had been dealt with already, but I am certainly willing to
file a feature request if necessary.

 Would the following be acceptable, BTW?

 |  [4, 5, 6][10]
 | IndexError: list index 10 out of range(3)
 |  [4, 5, 6][-4]
 | IndexError: list index -4 out of range(3)

That seems fine to me.

 Footnote: Based on 2.4.3 source, quite a few files, many with multiple
 lines to patch:

Holy cow! I can't believe that many changes would be necessary unless
the IndexError exception is scattered all over the place. I would hope
that one well-placed change could fix the bulk of cases.

Oh, and thanks for bringing your attention to this matter. This is one
of those little issues that comes up so often that I think fixing it
could make a significant difference in the overall efficiency of Python
programming.

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Re: problem formatting dates from text fields.

[Hendrik van Rooyen]

John Machin [EMAIL PROTECTED] wrote:
 Dennis Lee Bieber wrote:
8--
  Simplest is probably to do what many web-sites use for credit card
  expiration dates... Ignore any pre-built date-time modules...
 
  Create three integer fields, make the first two drop-down lists
  pre-populated with days and months. And validate the results later (just
  to cover someone putting in 31 02 ).
 

 My 2 cents worth:

 (1) this annoys the bejaysus out of data inputters who can type
 31\t12 a lot faster than they can pick it out of two drop-down lists.

 (2) this would annoy the bejaysus out of data users if they were aware
 of the extent of off-by-one errors caused by using drop-down lists.

 Cheers,
 John

This annoyance can be maximised if, after the selection, a pop up dialog window
is displayed showing what was chosen, along with the following text:

This is what you have chosen - Please indicate whether or not you wish to re
try

- with the focus on the yes button.
and then, when yes is chosen, to start again without any attempt to remember 
the previously entered values

- Hendrik


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Re: Video feature

[Lad]

Hello Tim,
Thank you for your reply.
Yes, my site uses Python.
Do you have any idea how to add video playing ( video streaming
feature)to my webiste?
Thank you for help
L.

Tim Roberts wrote:
 Lad [EMAIL PROTECTED] wrote:
 
 I would like  to add on my website  a possibility for visitors to
 upload video and watch other user's video. How much difficult would it
 be with Python?

 It's not all that hard, although you can probably download something that
 will do most of the job, probably in PHP.  Is your website already using
 Python?
 -- 
 Tim Roberts, [EMAIL PROTECTED]
 Providenza  Boekelheide, Inc.

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Re: A mail from Steve Ballmer. See what Microsoft will do and follow.

[James Stroud]

JustStand wrote:
 For detail, view http://www.homeoftester.com/viewtopic.php?t=281
 __
 I have a dream, I hope I can be as strong as Enter key.


Does this pointless blogvertisement in anyway compensate for the fact 
that windows sucks so hard?

James

-- 
James Stroud
UCLA-DOE Institute for Genomics and Proteomics
Box 951570
Los Angeles, CA 90095

http://www.jamesstroud.com/
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Re: Why not just show the out-of-range index?

[Bill Maxwell]

On Sun, 3 Dec 2006 23:31:56 -0500, Jean-Paul Calderone
[EMAIL PROTECTED] wrote:

On 3 Dec 2006 17:23:49 -0800, Russ [EMAIL PROTECTED] wrote:

 Rather, they (like I) will encourage to OP to submit a patch that fixes the 
 problem.

Now, that would be rather silly. I would have to familiarize myself
with the code for the Python interpreter, then send a patch to the
maintainers (and hope they notice it in their inboxes), while the
maintainers themselves could probably fix the problem in two minutes
flat. No thanks!

And I have some laundry that I would like you to do for me.  Let me know
when a convenient time for you to pick it up would be.

Jean-Paul


Are you saying that you place such low value on feedback from Python
users that you don't even want them to try and ask questions that might
help to improve the language?

In other words, if I'm not skilled or knowledgeable enough to improve
something myself, I shouldn't even mention it?


Bill


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RAD for python

[progman]

is there a  VB-alike  tool for python to create forms??

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algorithm for sorting functional expressions

[chrisguest]

I am trying to write some code that will take a list of functional
expressions, and order them so that those with primitive terms appear
at the beginning of the list and those that are defined by other terms
appear last.

eg:
getSortedEquations(['b = w + z','a = z - y','w = 2*z + v','z = e +
f','y = p + l']) =
['w = 2*z + v', 'z = e + f', 'y = p + l', 'b = w + z', 'a = z - 
y']

It is easy enough to tokenise each of the equations and produce a list
like:
 ['b', ['w','z']], ['a': ['z','y']], ['w':'z','v'] , ['z', ['e','f']],
['y',['p','l']]

But I'd like to find an algorithm that can handle the sorting problem.

So I suspect that this is a common problem for those familiar with
partially ordered sets or directed graphs. I'm wondering if anyone else
is familiar with this problem and knows an efficient algorithm that
will solve it. It would be good if any such algorithm would be able to
check for circular definitions in the input.

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Re: Why not just show the out-of-range index?

[Russ]

Dennis Lee Bieber wrote:

   OTOH: IndexError is something I seldom see -- most Python statements
 are intelligent enough to not need ad hoc indexing. About the only type
 that I've seen is just an, almost obvious, off-by-one problem...

   for i in xrange(len(a)):
   a[i] = a[i] + a[i+1]

 in which knowing the discrete values isn't that significant (to me, at
 least)

   It doesn't occur in things like

   for itm in a:

I agree that implicit indexing (your latter construct) is preferable to
explicit indexing if the index is not needed for any other purpose. But
sometimes the index itself is needed for some computation. And
sometimes a list is randomly accessed without a loop at all.

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Re: Why not just show the out-of-range index?

[Fredrik Lundh]

Russ wrote:

 Holy cow! I can't believe that many changes would be necessary unless
 the IndexError exception is scattered all over the place. I would hope
 that one well-placed change could fix the bulk of cases.

when you write x[i], the interpreter makes no assumptions about x and i 
and len(x); it just calls the corresponding method (__getitem__), either 
directly, or via a C-level internal slot.

there's no way to generate the error message you want in a single place 
without changing the semantics of x[i].

/F

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