[Tutor] New Python book

[Dick Moores]

Magnus Lie Hetland's new book, _Beginning Python: From Novice to
Professional_ was published by Apress on Sept. 26 (in the U.S.). My copy 
arrived in the mail a couple of days ago. Very much worth a look, IMHO. 
But what do the experts here think?

<http://www.bestbookdeal.com/book/compare/159059519X>

Dick Moores
[EMAIL PROTECTED]

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New Python book

[Dick Moores]

(Sorry, my previous post should not have had "Tutor" in the subject header.)

Magnus Lie Hetland's new book, _Beginning Python: From Novice to
Professional_ was published by Apress on Sept. 26 (in the U.S.). My copy
arrived in the mail a couple of days ago. Very much worth a look, IMHO.
But what do the experts here think?

<http://www.bestbookdeal.com/book/compare/159059519X>

Dick Moores
[EMAIL PROTECTED]


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Re: Book "Python and Tkinter Programming"

[Dick Moores]

DaveInSidney wrote at 15:55 10/8/2005:
>Check out BestBookBuys:
>http://www.bestwebbuys.com/Python_and_Tkinter_Programming-ISBN_1884777813.html?isrc=b-search

Or even better, BestBookDeal.com:
<http://www.bestbookdeal.com/book/compare/1884777813>

Dick Moores

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Compute pi to base 12 using Python?

[Dick Moores]

I need to figure out how to compute pi to base 12, to as many digits as 
possible. I found this reference, 
<http://mathworld.wolfram.com/Base.html>, but I really don't understand 
it well enough. Could someone show me how to do what I need?

Thanks,
Dick Moores
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Re: Compute pi to base 12 using Python?

[Dick Moores]

Bengt Richter wrote at 03:19 4/13/2005:
On Wed, 13 Apr 2005 02:06:11 -0700, Dick Moores <[EMAIL PROTECTED]> wrote:
>I need to figure out how to compute pi to base 12, to as many digits as
>possible. I found this reference,
><http://mathworld.wolfram.com/Base.html>, but I really don't understand
>it well enough. Could someone show me how to do what I need?
>
>Thanks,
>
>Dick Moores
>[EMAIL PROTECTED]
>
See if this is enough digits for homework? ;-)
This is not homework, nor am I a student, though I am trying to learn 
Python. I'm just trying to help an artist acquaintance who needs (I just 
learned) the first 3003 digits of pi to the base 12.

Hint: Lambert Meertens. Tweak the algorithm you find ;-)
Sorry. Your hint is beyond me.
Dick Moores
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Re: Compute pi to base 12 using Python?

[Dick Moores]

Dan Bishop wrote at 04:07 4/13/2005:
(3) A function for converting numbers to their base-12 representation.
For integers, this can be done with:
DIGITS = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
def itoa(num, radix=10):
   is_negative = False
   if num < 0:
  is_negative = True
  num = -num
   digits = []
   while num >= radix:
  num, last_digit = divmod(num, radix)
  digits.append(DIGITS[last_digit])
   digits.append(DIGITS[num])
   if is_negative:
  digits.append("-")
   digits.reverse()
   return ''.join(digits)
I see this works perfectly for integers. Thanks!
For a floating-point number x, the representation with d "decimal"
places count be found by taking the representation of int(round(x *
radix ** d)) and inserting a "." d places from the right.
But I'm sorry, but I can't follow you. I do have the first 1 or so 
places of pi base 10 (<http://mathwithmrherte.com/pi_digits.htm>), but 
could you show me what to do with, say, just 3.14159?

I apologize for being so dense.
Dick Moores
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Re: Compute pi to base 12 using Python?

[Dick Moores]

Bengt Richter wrote at 14:52 4/13/2005:
import sys
def main():
k, a, b, a1, b1 = 2L, 4L, 1L, 12L, 4L
while 1:
p, q, k = k*k, 2L*k+1L, k+1L
a, b, a1, b1 = a1, b1, p*a+q*a1, p*b+q*b1
d, d1 = a/b, a1/b1
while d == d1:
output(d)
a, a1 = 10L*(a%b), 10L*(a1%b1)
d, d1 = a/b, a1/b1
def output(d):
sys.stdout.write(`int(d)`)
sys.stdout.flush()
main()
# Reading/writing Python source often gives me the impression of
# reading/writing a poem!
# Layout, indentation, rythm, I like the look and feel!
# What does this tiny program do? It is not a sonnet, even not a
# pi-sonnet, but it surely produces Pi!
It sure does. When I ran it my jaw dropped. I had 7,947 CORRECT digits in 
2 minutes 0 seconds (by my stopwatch)!

Now on to base 12.
Thanks!
Dick Moores
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Re: Compute pi to base 12 using Python?

[Dick Moores]

Dan wrote at 18:02 4/13/2005:
On Wed, 13 Apr 2005 03:27:06 -0700, Dick Moores <[EMAIL PROTECTED]>
wrote:
> I'm just trying to help an artist acquaintance who needs (I just
>learned) the first 3003 digits of pi to the base 12.
Now you've got me curious.  Why would an artist want the first 3003
digits of pi to the base 12?
He says,
Do you know how I can get "base12 pi"?
Because the chromatic scale is base12.
c c# d d# e f f# g g# a a# b
Dick
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Re: Compute pi to base 12 using Python?

[Dick Moores]

Paul Rubin wrote at 18:20 4/13/2005:
Dick Moores <[EMAIL PROTECTED]> writes:
> I need to figure out how to compute pi to base 12, to as many digits
> as possible. I found this reference,
> <http://mathworld.wolfram.com/Base.html>, but I really don't
> understand it well enough. Could someone show me how to do what I need?
Using the GNU "bc" utility:
  $ bc -l
  bc 1.06
  Copyright 1991-1994, 1997, 1998, 2000 Free Software Foundation, Inc.
  This is free software with ABSOLUTELY NO WARRANTY.
  For details type `warranty'.
  scale = 3000# number of output places wanted
  obase = 12  # output base
  print 4 * a(1)  # pi = 4*arctan(1)
I don't believe GNU "bc" is available for Windows, is it?
Thanks,
Dick Moores
[EMAIL PROTECTED] 

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Re: Compute pi to base 12 using Python?

[Dick Moores]

Doug Schwarz wrote at 20:14 4/13/2005:
In article <[EMAIL PROTECTED]>,
 Dick Moores <[EMAIL PROTECTED]> wrote:
> Dan wrote at 18:02 4/13/2005:
> >On Wed, 13 Apr 2005 03:27:06 -0700, Dick Moores <[EMAIL PROTECTED]>
> >wrote:
> >
> > > I'm just trying to help an artist acquaintance who needs (I just
> > >learned) the first 3003 digits of pi to the base 12.
> >
> >Now you've got me curious.  Why would an artist want the first 3003
> >digits of pi to the base 12?
>
> He says,
> Do you know how I can get "base12 pi"?
> Because the chromatic scale is base12.
> c c# d d# e f f# g g# a a# b
>
> Dick
Does your artist friend have any idea what base 12 means?
The chromatic scale is based on one twelfth powers of two, i.e., if the
frequency of a note in the scale is f(n), then the frequency of the next
note is given by
  f(n+1) = f(n) * 2^(1/12)
so by the time you go all 12 notes in an octave you have doubled the
frequency.  There is nothing here involving base 12 or pi.
He's a friend of a friend. I don't know what he knows, but I'll forward 
this to MY friend. Thanks.

Dick

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Re: Compute pi to base 12 using Python?

[Dick Moores]

Steve Holden wrote at 22:29 4/13/2005:
Dick Moores wrote:
Steve Holden wrote at 19:12 4/13/2005:
Dick Moores wrote:
Dan wrote at 18:02 4/13/2005:
On Wed, 13 Apr 2005 03:27:06 -0700, Dick Moores <[EMAIL PROTECTED]>
wrote:
> I'm just trying to help an artist acquaintance who needs (I just
>learned) the first 3003 digits of pi to the base 12.
Now you've got me curious.  Why would an artist want the first 3003
digits of pi to the base 12?

He says,
Do you know how I can get "base12 pi"?
Because the chromatic scale is base12.
c c# d d# e f f# g g# a a# b
Dick
So it's, like, the guy is going to "play pi"? So why does the melody 
have 3003 notes?
Sorry, he's just a friend of a friend. If I find out I'll post. Here's 
his site if you want to poke around for yourself. Maybe his email 
address is there.
Dick
Where?
Sorry about that. <http://www.kenjikojima.com/>
Dick
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Re: Compute pi to base 12 using Python?

[Dick Moores]

Dick Moores wrote at 18:40 4/14/2005:
Sorry about that. <http://www.kenjikojima.com/>
I just listened to Kojima's
"NEW
Chorus Pi (Japanese) / 2:28
Chorus: MacinTalk Voices. The music was created from the constant PI."
on that page. The vocal is singing the digits of base-10 pi.
ten is . or decimal point
zero is 0
inchi is 1
ni is 2
san is 3
ta? is 4 (don't understand that "ta" or "tan", but it must be 4)
go is 5
roku is 6 -- in the music 6 sounds like "raku"
nana is 7
hachi is 8
ku is 9
Take a look/listen to
"String Quartet Pi / 5:06 and the process of data
The music was created from the constant PI (3.141592...) to 3,000 
decimal places by programming."

Lots of details there on the music.
Dick


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Re: Compute pi to base 12 using Python?

[Dick Moores]

M.E.Farmer wrote at 23:18 4/14/2005:
Nice collection of unix tools, Cygwin not needed.
http://unxutils.sourceforge.net/
Thank you!
But a question. I've download both UnxUtils.zip and UnxUpdates.zip. I'm 
planning to put the contents of UnxUtils.zip in a directory and then move 
the contents of UnxUpdates.zip, which has many of the same filenames, to 
the same directory. Should I just let Windows replace the old files with 
the updated ones?

This seems obvious, but I wanted to make sure.
I'm using Win XP Pro.
Thanks,
Dick Moores

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Re: Compute pi to base 12 using Python?

[Dick Moores]

Tim Roberts wrote at 22:05 4/16/2005:
Dick Moores <[EMAIL PROTECTED]> wrote:
>>
>># Reading/writing Python source often gives me the impression of
>># reading/writing a poem!
>># Layout, indentation, rythm, I like the look and feel!
>>
>># What does this tiny program do? It is not a sonnet, even not a
>># pi-sonnet, but it surely produces Pi!
>
>It sure does. When I ran it my jaw dropped. I had 7,947 CORRECT digits in
>2 minutes 0 seconds (by my stopwatch)!
How do you know?  I think the 7,912th digit is wrong.
;)
I suppose you're joshing, Tim, but I really did check by using my trusty

def compareSequences(seq1, seq2):
"""
find first index at which two sequences differ
"""
if s1 == s2:
print "Sequences are identical"
return None
if len(seq1) >= len(seq2):
shorterOrEqualSequence = seq2
else:
shorterOrEqualSequence = seq1
for index in range(len(shorterOrEqualSequence)):
if seq1[index] != seq2[index]:
print "sequences first differ at index", index
print "s1 at that index is", s1[index]
print "s2 at that index is", s2[index]
break
if index == len(shorterOrEqualSequence)-1:
print "sequences are identical thru end of shorter sequence at 
index", index
==

I got the "correct" pi from 
<http://www.ballandclaw.com/upi/pi.5.html>. By inspection of the text 
file I copied this to (removing the "3." of "3.1"), the 7,912th digit is 
"2" (I'm using Textpad). If you begin with "31", which what the speedy 
script does, the 7,912th digit is "6".

Now, I've shown you mine. Show me yours. ;-)
Dick 

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Re: Compute pi to base 12 using Python?

[Dick Moores]

M.E.Farmer wrote at 23:18 4/14/2005:
> >Using the GNU "bc" utility:
> >
> >   $ bc -l
> >   bc 1.06
> >   Copyright 1991-1994, 1997, 1998, 2000 Free Software Foundation,
Inc.
> >   This is free software with ABSOLUTELY NO WARRANTY.
> >   For details type `warranty'.
> >   scale = 3000# number of output places wanted
> >   obase = 12  # output base
> >   print 4 * a(1)  # pi = 4*arctan(1)
Wow! this got me the 3003 (changed from 3000) digits of pi to base 12 in 
60.8 secs. No, I didn't count them yet, nor am I sure they're correct. 
But I'd bet on them..

Could someone remind me how to get the output of bc -l into a text file 
on Windows? (I've tried employing " > pi3003.txt" in various ways) OR, 
how to copy and paste from the command line window, or whatever that 
window is called? (Sorry for the OT question.)

BTW I found a nice set of SCO UNIX man pages at .
Dick
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Re: Compute pi to base 12 using Python?

[Dick Moores]

Roel Schroeven wrote at 01:45 4/17/2005:
Dick Moores wrote:
M.E.Farmer wrote at 23:18 4/14/2005:
> >Using the GNU "bc" utility:
> >
> >   $ bc -l
> >   bc 1.06
> >   Copyright 1991-1994, 1997, 1998, 2000 Free Software Foundation,
Inc.
> >   This is free software with ABSOLUTELY NO WARRANTY.
> >   For details type `warranty'.
> >   scale = 3000# number of output places wanted
> >   obase = 12  # output base
> >   print 4 * a(1)  # pi = 4*arctan(1)
Wow! this got me the 3003 (changed from 3000) digits of pi to base 12 
in 60.8 secs. No, I didn't count them yet, nor am I sure they're 
correct. But I'd bet on them..
Could someone remind me how to get the output of bc -l into a text file 
on Windows? (I've tried employing " > pi3003.txt" in various ways) OR, 
how to copy and paste from the command line window, or whatever that 
window is called? (Sorry for the OT question.)
Works for me (using the Cygwin version though) when I do
C:\cygwin\bin\bc -l > pi12.txt
But how or when do you enter the lines
scale = 3000
obase = 12
print 4 * a(1)
Otherwise, to copy from the command prompt window: open the system menu
(icon in the top left corner of the window) and choose Edit->Mark. Then
select what you want to copy and press Enter or choose Edit->Copy in the
system menu.
Thanks! You've just relieved years of frustration.
Dick 

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Re: Compute pi to base 12 using Python?

[Dick Moores]

Bengt Richter wrote at 02:26 4/17/2005:
>Could someone remind me how to get the output of bc -l into a text file
>on Windows? (I've tried employing " > pi3003.txt" in various ways) OR,
>how to copy and paste from the command line window, or whatever that
>window is called? (Sorry for the OT question.)
To copy from the command window to the clipboard:
1. Scroll top of desired stuff to make it visible near top
2. Hold down Alt
3. Tap Space Bar
4. Release Alt
5. Tap e
6. Tap k
7. Use mouse or arrow keys to place cursor on top left corner of desired box
8. Hold down Shift
9. Use arrow keys or mouse-with-left-button-pressed to go to bottom 
right character of desired box
9a. If the bottom is out of sight, keep holding  shift down and pretend 
you can cursor down below bottom.
the attempt should make the screen scroll up and select more 
desired material. If you overshoot, don't panic,
just keep holding down shift and use arrows (the are slower) or 
mouse-with-left-button-still-down to move to
desired bottom right corner.
10. Release mouse button if using that
11. Release Shift
12. Press Enter
That should copy to the clipboard and make the selection box revert to 
normal display.

Pasting from clipboard is up to you. Pasting into the command window 
from clipboard
is 2-5 above, and Tap p
Thanks for showing me another way. But Roel Schroeven's
"to copy from the command prompt window: open the system menu
(icon in the top left corner of the window) and choose Edit->Mark. Then
select what you want to copy and press Enter or choose Edit->Copy in the
system menu."
seems to be easier.

PS. Redirecting with > from a script whose interpreter was started by 
windows extension association
doesn't work on some version of windows. To be safe, invoke the 
interpreter explicitly, e.g.,
python myscript.py [whatever args here] > pi3003.txt
Thanks very much for this.
What kind of args could I use here?
Dick
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Re: Compute pi to base 12 using Python?

[Dick Moores]

Paul Rubin wrote at 02:35 4/17/2005:
Dick Moores <[EMAIL PROTECTED]> writes:
> >C:\cygwin\bin\bc -l > pi12.txt
>
> But how or when do you enter the lines
>
> scale = 3000
> obase = 12
> print 4 * a(1)
You could put them into a file, say pi.bc.  Then run
  bc -l pi.bc
OK, now that I've got Textpad trained to open .bc files, I'm thinking of 
things to store in them. I'm sure I'll want to put in some remarks as 
well. What should I use to mark the remarks. "#", "//", or what?

The bc man page at <http://www.rt.com/man/bc.1.html> is tough. Any 
suggestion for more easily understandable help?

And finally (maybe), is it possible to employ bc within a Python script?
Thanks,
Dick

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Programming Python, 3rd ed.??

[Dick Moores]

Several months ago I saw an item on the O'Reilly site to the effect that 
the 3rd. ed. of Programming Python was in the works. I made a note to 
myself to check back in January. I just did, but could find nothing at 
all about a 3rd. edition. Anyone know?

Thanks,

Dick Moores

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Need Python for Linux (Suse 10.1)

[Dick Moores]

I've got a friend interested in trying out Python. I sent him to

http://www.python.org/download/linux/ but he's uncertain as to what
to download. He's rather get a new download than use what was on his Suse
disk. His box is an x86.
Any chance
Python
2.4.3 compressed source tarball would be suitable for him?
Advice for him, please.
Thanks,
Dick Moores




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Re: Looking for the Perfect Editor

[Dick Moores]

At 01:10 PM 9/8/2006, Doug Stell wrote:
>Try www.TextPad.com. I've used it for years and love it. It
>understands many programming language constructs and can be taught to
>understand python so that things show up in color.

Any tips on how to teach TextPad to understand python?

Thanks,

Dick Moores

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Re: Looking for the Perfect Editor

[Dick Moores]

At 02:15 PM 9/10/2006, Kent Johnson wrote:
>Dick Moores wrote:
> > At 01:10 PM 9/8/2006, Doug Stell wrote:
> >> Try www.TextPad.com. I've used it for years and love it. It
> >> understands many programming language constructs and can be taught to
> >> understand python so that things show up in color.
> >
> > Any tips on how to teach TextPad to understand python?
>Download and install the Python syntax highlighting definition from the
>TextPad website.

Thanks very much, Kent. I've been using TextPad for 10 years and 
never considered using it for Python.

I downloaded Python (7) from 
http://www.textpad.com/add-ons/synn2t.html and put the file 
PythonV2.4.syn in C:\Program Files\TextPad 4\system .

>I make a tool to run the front window in Python. Here are the values
>from the preferences window for the tool:
>
>Command: C:\Python24\python.exe
>Parameters: -u $File
>Init fldr: $FileDir
>
>regex to match output:
>^.*"([^"]+)", *line ([0-9]+)
>
>with File: 1, Line: 2

After fumbling around, I believe I've made the tool, using your 
values, except I used E:\Python24\python.exe instead of 
C:\Python24\python.exe .

I also associated .py with TextPad. I'm now able to open a Python 
script with TextPad, and execute it with  Ctrl+4.

However, no syntax highlighting is showing up. so I must have done 
something wrong. Do I have to do something other than put 
PythonV2.4.syn in C:\Program Files\TextPad 4\system ?

Also, why do you use TextPad instead of IDLE?

Thanks,

Dick Moores


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Re: Looking for the Perfect Editor

[Dick Moores]

At 06:30 PM 9/10/2006, Kent Johnson wrote:
>Dick Moores wrote:
>
> > I downloaded Python (7) from
> > http://www.textpad.com/add-ons/synn2t.html and put the file
> > PythonV2.4.syn in C:\Program Files\TextPad 4\system .
> >
> > However, no syntax highlighting is showing up. so I must have done
> > something wrong. Do I have to do something other than put
> > PythonV2.4.syn in C:\Program Files\TextPad 4\system ?
>
>One more step - make a new Document Class for Python (in the prefs).
>Associate it with *.py, turn on syntax highlighting and select the
>syntax file you downloaded.

OK. Done.

> > Also, why do you use TextPad instead of IDLE?
>
>You're kidding, right?

No. Tell me, please. Macros? Comparing files? What else?

Dick



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Re: Looking for the Perfect Editor

[Dick Moores]

At 08:54 PM 9/13/2006, Jay wrote:
>I, too, am a hardcore fan of jEdit.  It's nice to finally see some user
>support on this forum.  :-)

I'm trying out jEdit and UliPad. I got UliPad going right away and 
I'm very pleased with it, but could I jump in here with a basic jEdit 
question? How do you run a script?

And one more. On the menus, the font is clear and large, but the 
equivalent key combinations are written so small they are very 
difficult for me to read. Is there a way to configure them to be 
slightly larger? (I'd ask on the jEdit support forum, but it doesn't 
seem to be very active.)

Thanks,

Dick Moores




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Re: Looking for the Perfect Editor

[Dick Moores]

At 08:51 AM 9/14/2006, stu wrote:

>Dick Moores wrote:
> > I'm trying out jEdit and UliPad. I got UliPad going right away and
> > I'm very pleased with it, but could I jump in here with a basic jEdit
> > question? How do you run a script?
> >
> > And one more. On the menus, the font is clear and large, but the
> > equivalent key combinations are written so small they are very
> > difficult for me to read. Is there a way to configure them to be
> > slightly larger? (I'd ask on the jEdit support forum, but it doesn't
> > seem to be very active.)
> >
>
>to change jedits fonts, under utilities menu choose global options
>
>select appearance, this has font options for menus + other fields
>text area has the editing text font (I use dialogeinput for menus and
>such and
>andale mono for the text area...)

I afraid I still don't see how to use larger fonts for the problem I 
mentioned. I mean the tiny fonts used, for example, to the right of 
File | New, where it says, I'm guessing, "C+n".

>to run a script.. you can 'dock' jython in the sides of the editor or
>bottom, and import from the buffer or load it.. or fire jython up from
>the plugin menu

Doesn't sound easy. With UliPad (or IDLE, for that matter) just hit F5.

>there is also a colour scheme plugin that gives you colour defaults if
>you want it to look lke emacs or jbuilder or idea etc etc etc
>
>jedit is pretty rich with its plugins.

Thanks,

Dick



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Re: Problem with following python code

[Dick Moores]

At 09:52 PM 6/11/2007, Dan Hipschman wrote:
>On Tue, Jun 12, 2007 at 04:25:31AM -, why? wrote:
> > I've been having problem with the following code. It's supposed to
> > print the prime numbers  between 10 and 100. But i'm not getting any
> > output, i.e. i guess the outer 'for' loop is being traversed only
> > once. I would be greatful if you could help me out. Thanx!
> > >>> f=1
> > >>> for i in range(10,100):
> > ... for j in range(2,i):
> > ... if i%j==0:
> > ... f=0
> > ... break
> > ... else: continue
> > ... if f==1:
> > ... print i,
> > ...
>
>Move "f=1" inside the outer loop:
>
>for i in range(10,100):
> f=1
> for j in range(2,i):
> if i%j==0:
> f=0
> break
> else: continue
> if f==1:
> print i,
>
>It gets set to 0 in the first iteration and never has another chance to
>be set to 1 after that.

And of course the inner loop does too much work. Try:

for i in range(10,100):
     f=1
 max = int(i**.5 + 1)
 for j in range(2,max):
 if i%j==0:
 f=0
 break
 else: continue
 if f==1:
 print i,

Dick Moores

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Looking for a wxPython GUI builder

[Dick Moores]

How about SPE?

Any others?

And which ones do people
actually use? Commercial or Freeware.

Thanks,

Dick Moores

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Re: preferred windows text editor?

[Dick Moores]

At 11:06 AM 5/9/2007, T. Crane wrote:
>Right now I'm using Notepad++.  What are other people using?

Ulipad.

Dick Moores


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Re: OOP in Python book?

[Dick Moores]

At 08:41 AM 7/27/2007, Bill wrote:
>Does anyone out there have any information about this book. It's
>listed on Amazon to be published in November of this year. A simple
>Google search (1st page only) doesn't show anything useful, and I
>can't find a reference on the web sites of the authors. Neither of the
>authors appears to be heavily into OOP theory, just some CS areas that
>I don't understand.
>
>I'm particularly interested in why this book is worth the $100 tag
>that Amazon shows.

Well, the publisher is Prentice Hall, "The world's leading 
educational publisher". Textbooks are typically expensive.

Here's the Amazon link: 
<http://www.amazon.com/Object-Oriented-Programming-Python-Michael-Goldwasser/dp/0136150314>

Dick Moores


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Re: OOP in Python book?

[Dick Moores]

At 01:27 PM 7/28/2007, Dennis Lee Bieber wrote:
>On Fri, 27 Jul 2007 16:27:57 -0700, Dick Moores <[EMAIL PROTECTED]>
>declaimed the following in comp.lang.python:
>
>
> > Well, the publisher is Prentice Hall, "The world's leading
> > educational publisher". Textbooks are typically expensive.
> >
>
> Yeah... But at that price it should have hard-covers!

Should have, but look at this popular Cultural Anthropology text 
(paperback): <http://tinyurl.com/38ec5s>. List price is $120.95 USD. 
(BTW I just bought the 6th edition online for about $10.)

Then there's Calculus: Single Variable (Paperback) 
<http://tinyurl.com/2lqw9c> List price $123.95 USD.

And so it goes.

Dick


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Re: the one python book

[Dick Moores]

At 10:22 AM 8/5/2007, vasudevram wrote:
> > On Aug 4, 7:23 am, "dhr" <[EMAIL PROTECTED]> wrote:
> >
> > > newbie question:
> >
> > > Is there a 'K&R" type of Python book? The book that you'd better have on
> > > your shelf if you are going into Python?
> >
>
>Python in a Nutshell, the Python Cookbook and Programming Python are
>all very good, IMO. Programming Python comes with a CD of all the
>source code in the book (at least the 2nd edition did, as well as
>Python language - this can save you some time keying in the examples.
>Of course, many of the O'Reilly books (and all 3 of these are from
>O'Reilly) have links to downloadable source code from them. Just
>Google for the name of the book, then in the results, hit the
>appropriate link to the O'Reilly site for the book, and look down the
>page for the link to the examples' source.
>
>Or (for Programming Python):
>
>http://www.oreilly.com/catalog/python2/
>http://www.oreilly.com/catalog/python3/

No CD with 3rd edition, but here are the examples: 
<http://examples.oreilly.com/python3/>

Dick Moores

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WinPdb?

[Dick Moores]

The only debugging I've done so far is to put in print statements where I
want to see what's happening. But it's often "through a glass
darkly".
However, I just discovered that my excellent (IMO) Python editor, Ulipad,
comes with WinPdb, and I'm thinking it's about time I learned how to use
a debugger. 
But first, could I get some reviews here of WinPdb before I invest a lot
of time in learning it? I've found a couple links to tutorials on the
WinPdb website
(<
http://www.digitalpeers.com/pythondebugger/>, where you'll also
notice that version 1.2.0 came out August 6 (the latest svn revision of
Ulipad already has it:
<
http://ulipad.googlecode.com/svn/> (Ulipad's developer, Limodou,
is very responsive). 
Thanks,
Dick Moores

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Puzzled by "is"

[Dick Moores]

 >>> () is ()
True
 >>> (1,) is (1,)
False

Why?

Thanks,

Dick Moores

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Re: Puzzled by "is"

[Dick Moores]

At 10:46 AM 8/9/2007, Bill Scherer wrote:
>Dick Moores wrote:
> >  >>> () is ()
> > True
> >  >>> (1,) is (1,)
> > False
> >
> > Why?
> >
>
> >>> a = ()
> >>> b = ()
> >>> c = (1,)
> >>> d = (1,)
> >>> a is b
>True
> >>> c is d
>False
> >>> id(a)
>3086553132
> >>> id(b)
>3086553132
> >>> id(c)
>3086411340
> >>> id(d)
>3086390892
>
>
>There is only one empty tuple.
>Does that clear it up for you?

But isn't that the same as saying, "That's just the reality of 
Python; it is what it is."? I want to know why there is only one 
empty tuple, but more than one (1,).

Also,
 >>> [] is []
False

Dick  

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Re: Puzzled by "is"

[Dick Moores]

At 06:13 PM 8/9/2007, Ben Finney wrote:
>Content-Transfer-Encoding: base64Grzegorz 
>Słodkowicz <[EMAIL PROTECTED]  [EMAIL PROTECTED] 
>theorisation but I'd rather expect the interpreter
> > simply not to create a second tuple while there already is an
> > identical one.
>
>Others have already said that it's an implementation optimisation,
>which seems to partly answer your question.
>
>It's important to also realise that the language is *deliberately*
>non-committal on whether any given value will have this behaviour;
>that is, it's entirely left to the language implementation which
>optimisation trade-offs to make, and the language user (that's you and
>I) should *not* expect any particular behaviour to hold between
>different implementations.

I'm not clear on the meaning of "implementations" 
here.  Would 2.5 for Windows, Mac, Linux all be 
different implementations? Would Iron Python be another? ActivePython?

Thanks,

Dick


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Re: Puzzled by "is"

[Dick Moores]

On 8/12/07, Ben Finney <[EMAIL PROTECTED]> wrote:
>
> Dick Moores <[EMAIL PROTECTED]> writes:
>
> > At 06:13 PM 8/9/2007, Ben Finney wrote:
> > >it's entirely left to the language implementation which
> > >optimisation trade-offs to make, and the language user (that's you
> > >and I) should *not* expect any particular behaviour to hold between
> > >different implementations.
> >
> > I'm not clear on the meaning of "implementations" here.  Would 2.5
> > for Windows, Mac, Linux all be different implementations? Would Iron
> > Python be another? ActivePython?
>
> For the purpose of the above statement, you should consider even the
> same Python on two different machines to be "different
> implementations". As a programmer writing Python code, you should not
> expect any "implementation-dependent" behaviour to operate in any
> particular way.


So would a programmer EVER use "is" in a script?

Dick
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Re: Puzzled by "is"

[Dick Moores]

At 08:23 AM 8/12/2007, Steve Holden wrote:
>Dick Moores wrote:
> > So would a programmer EVER use "is" in a script?
>
>Sure. For example, the canonical test for None uses
>
>  x is None
>
>because there is only ever one instance of type Nonetype, so it's the
>fastest test. Generally speaking you use "is" to test for identity (do
>these two expressions reference the same object) rather than equality
>(do these two expressions evaluate to equivalent objects).

Off the top of your head, could you or others give me as many 
examples as you can think of?

Thanks again,

Dick


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Re: Puzzled by "is"

[Dick Moores]

At 09:59 AM 8/12/2007, Steve Holden wrote:
>Dick Moores wrote:
> > At 08:23 AM 8/12/2007, Steve Holden wrote:
> >> Dick Moores wrote:
> >>> So would a programmer EVER use "is" in a script?
> >> Sure. For example, the canonical test for None uses
> >>
> >>  x is None
> >>
> >> because there is only ever one instance of type Nonetype, so it's the
> >> fastest test. Generally speaking you use "is" to test for identity (do
> >> these two expressions reference the same object) rather than equality
> >> (do these two expressions evaluate to equivalent objects).
> >
> > Off the top of your head, could you or others give me as many
> > examples as you can think of?
> >
>Occasionally it's necessary to test for a specific type (though in
>Python this is usually bad practice). Since types are also singletons
>the best way to do this is (e.g.):
>
>  type(x) is type([]) # test specifically for a list
>
>If you want to know whether you have been told to write to standard
>output, one possible test is
>
>  if f is not sys.stdout
>
>Similarly, of course, you can test for the other standard IO channels.
>
>The imputil module contains the test
>
>  if importer is not self
>
>to determine whether a reload() should be performed in the context of
>the current package.
>
>When you need to establish a specific sentinel value that can never be
>provided by an outside caller it's normal to create an instance of
>object (the simplest possible thing you can create in a Python program)
>and test for that instance, as in
>
>  sentinel = object()
>  ...
>  if value is sentinel:
>
>You can test whether a class is new-style as opposed to old-style, which
>can help to unify old-style and new-style objects:
>
>class MetaProperty(type):
>  def __new__(cls, name, bases, dct):
>  if bases[0] is object: # allow us to create class Property
>  return type.__new__(cls, name, bases, dct)
>  return property(dct.get('get'), dct.get('set'),
>  dct.get('delete'), dct.get('__doc__'))
>
>  def __init__(cls, name, bases, dct):
>  if bases[0] is object:
>  return type.__init__(cls, name, bases, dct)
>
>
>That gets you started ...

Sure does. Thanks very much, Steve.

Dick


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A dumb question about a class

[Dick Moores]

I'm still trying to understand classes. I've made some progress, I 
think, but I don't understand how to use this one. How do I call it, 
or any of its functions? It's from the Cookbook, at 
<http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/523048>.

Thanks,

Dick Moores

=
class PrimeList:
def __init__(self, initial=0):
self.primelist = [2,3]
self.primelookup = [0,0,1,1]
self.max_prime = 3
self.grow_primelist(initial)

def grow_primelist(self,number):
newprimes = []
while self.max_prime <= number:
next = self.nextprime()
newprimes.append(next)
self.max_prime = next
size_difference = self.max_prime - 
len(self.primelookup) + 1
self.primelookup.extend([0] * size_difference)
for i in newprimes:
self.primelookup[i]=1

def contains(self,number):
if number < 2:
return 0
if number > len(self.primelookup) - 1:
self.grow_primelist(number)
return self.primelookup[number]
return self.primelookup[number]

def nextprime(self):
i = self.max_prime + 2
while 1:
isprime = True
for prime in self.primelist:
if i % prime == 0:
isprime = False
i += 2
break
if isprime:
self.primelist.append(i)
return(i)
==

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Re: A dumb question about a class

[Dick Moores]

At 03:09 PM 8/12/2007, Steven Bethard wrote:

>Here's how I'd write the recipe::
>
>  import itertools
>
>  def iter_primes():
>  # an iterator of all numbers between 2 and +infinity
>  numbers = itertools.count(2)
>
>  # generate primes forever
>  while True:
>
>  # get the first number from the iterator (always a prime)
>  prime = numbers.next()
>  yield prime
>
>  # remove all numbers from the (infinite) iterator that are
>  # divisible by the prime we just generated
>  numbers = itertools.ifilter(prime.__rmod__, numbers)
>
>
>  class PrimeList(object):
>  def __init__(self):
>  # infinite iterator of primes
>  self._prime_iter = iter_primes()
>
>  # the last prime we've seen
>  self._last_prime = None
>
>  # all primes seen so far
>  self._prime_set = set()
>
>  # add the first prime (so that _last_prime is set)
>  self._add_prime()
>
>  def __contains__(self, n):
>  # add primes to the list until we exceed n
>  while n > self._last_prime:
>  self._add_prime()
>
>  # return True if n is one of our primes
>  return n in self._prime_set
>
>  def _add_prime(self):
>  # take a prime off the iterator and update the prime set
>  self._last_prime = self._prime_iter.next()
>  self._prime_set.add(self._last_prime)

I'm afraid my next question is "How do I run this"?

Dick


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Re: A dumb question about a class

[Dick Moores]

At 03:35 PM 8/12/2007, Steven Bethard wrote:
>Note that if you just want to iterate over all the primes, there's no
>need for the class at all.  Simply write::
>
>  for prime in iter_primes():

Even if I want to test only 1 integer, or want the list of primes in 
a certain interval, I don't need the class at all:


import itertools

def iter_primes():
 # an iterator of all numbers between 2 and +infinity
 numbers = itertools.count(2)


 # generate primes forever
 while True:


 # get the first number from the iterator (always a prime)
 prime = numbers.next()
 yield prime


 # remove all numbers from the (infinite) iterator that are
 # divisible by the prime we just generated
 numbers = itertools.ifilter(prime.__rmod__, numbers)

def listPrimes(n,m):
 """
 Returns the list of primes in closed interval [n,m]
 """
 primes = []
 for prime in iter_primes():
 if prime > m:
 return primes
 if n <= prime <= m:
 primes.append(prime)


Thanks for your help. I didn't learn much about classes, but 
appreciated your iter_primes() a lot!

Dick Moores 

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Re: Binary, Hex, and Decimal string conversions

[Dick Moores]

At 04:20 PM 8/12/2007, Robert Dailey wrote:
Well, I decided to implement my
own way of doing this. I've attached the source. You're all welcome
:)
On 8/12/07, Michael Bentley
<
[EMAIL PROTECTED]> wrote:


Hi Robert,

On Aug 11, 2007, at 3:59 PM, Robert Dailey wrote:

Hi, I was wondering if there is a built in module that supports
conversion in any direction between Binary, Hex, and Decimal strings?
Thanks. 

Shouldn't be too hard to build one.  Here's a little incantation
to convert from base 10 to another base:

import string

def to_base(number, base):

'converts base 10 integer to another base'

number = int(number)

base = int(base)

if base < 2 or base > 36:

raise ValueError, "Base must be between 2 and 36" 

if not number:

return 0

symbols = string.digits + string.lowercase[:26]

answer = []

while number:

number, remainder = divmod(number, base)

answer.append(symbols[remainder]) 

return ''.join(reversed(answer))

I've tried to figure out the correct indentation for this, and came up
with

import string
def to_base(n, base):
    'converts base 10 integer to another base, up thru
base 36'
    n = int(n)
    base = int(base) 
    if base < 2 or base > 36:
    raise ValueError, "Base
must be between 2 and 36" 
    if not n:
    return 0
    symbols = string.digits + string.lowercase[:26] 
    answer = []
    while n:
    n, remainder = divmod(n,
base)
   
answer.append(symbols[remainder]) 
    return ''.join(reversed(answer))
n = 12
base = 36
print to_base(n, base)
==
This seems to work fine for n >= base, but not for n < base. For
example, the code shown returns "c". Is my indentation wrong,
or the code? It seems to me that the code should work for the general
case, not just for n >= base.
Dick Moores


How 'bout you hack a from_base function and email it back to me?
(hint: type 'help(int)' in the python interpreter).

Peace,

Michael

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Content-Type: text/plain; name="baseconv.py"
Content-Disposition: attachment; filename="baseconv.py"
X-Attachment-Id: f_f5a5roa4

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Re: Binary, Hex, and Decimal string conversions

[Dick Moores]

At 07:04 PM 8/12/2007, Michael Bentley wrote:

>On Aug 12, 2007, at 6:28 PM, Dick Moores wrote:
>
>>n = 12
>>base = 36
>>print to_base(n, base)
>>==
>>This seems to work fine for n >= base, but not for n < base. For 
>>example, the code shown returns "c". Is my indentation wrong, or 
>>the code? It seems to me that the code should work for the general 
>>case, not just for n >= base.
>
>Isn't 'c' the correct answer?

Yes, of course. Stupid of me.

Dick


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Re: Binary, Hex, and Decimal string conversions

[Dick Moores]

At 07:35 AM 8/13/2007, Robert Dailey wrote:
Just curious Dick, why are you
making your own to_base method? Doesn't the source I provided in my
earlier email give you all that you need? I was hoping my source might be
useful to a few people, even though it's pretty trivial code.

I didn't roll my own. I just preferred "n" to
"number".  I greatly appreciated your code!
Dick

On 8/12/07, Dick Moores
<[EMAIL PROTECTED]> wrote:


At 07:04 PM 8/12/2007, Michael Bentley wrote:

>On Aug 12, 2007, at 6:28 PM, Dick Moores wrote:

>

>>n = 12

>>base = 36

>>print to_base(n, base)

>>== 

>>This seems to work fine for n >= base, but not for n <
base. For

>>example, the code shown returns "c". Is my
indentation wrong, or

>>the code? It seems to me that the code should work for the
general 

>>case, not just for n >= base.

>

>Isn't 'c' the correct answer?

Yes, of course. Stupid of me.

Dick


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Opinions about this new Python book?

[Dick Moores]

I'd appreciate opinions about this new Python book.

Title: Python Power!: The Comprehensive Guide
Author:  Matt Telles
Publisher:  Course Technology
Pub. Date:  Jul 27, 2007
Edition:  1st edition
Binding:  Paperback
Pages:  508
ISBN:  1598631586
List Price:  34.99 USD

The book on the publisher's website: <http://tinyurl.com/2dkhzg>

And at BestBookDeal.com:
< http://www.bestbookdeal.com/book/compare/1598631586>

Thanks,

Dick Moores 

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Re: Opinions about this new Python book?

[Dick Moores]

At 05:57 AM 8/14/2007, [EMAIL PROTECTED] wrote:
>On Aug 14, 7:05 am, Dick Moores <[EMAIL PROTECTED]> wrote:
> > I'd appreciate opinions about this new Python book.
> >
> > Title: Python Power!: The Comprehensive Guide
> > Author:  Matt Telles
> > Publisher:  Course Technology
> > Pub. Date:  Jul 27, 2007
> > Edition:  1st edition
> > Binding:  Paperback
> > Pages:  508
> > ISBN:  1598631586
> > List Price:  34.99 USD
> >
> > The book on the publisher's website: <http://tinyurl.com/2dkhzg>
> >
> > And at BestBookDeal.com:
> > <http://www.bestbookdeal.com/book/compare/1598631586>
> >
> > Thanks,
> >
> > Dick Moores
>
>I just got this book over the weekend. I'll start reading/skimming
>through it this week and hopefully remember to get back to you.

Thanks!

>  By the
>way, why do you want to know?

If the experts like it, I'll buy it.

Dick


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Re: Hot subject: a good python editor and/or IDE?

[Dick Moores]

At 02:47 AM 8/19/2007, Sébastien wrote:
>Hi folks,
>
>I am currently using Eclipse+PyDev when developping Python projects but
>I lack a fast, simple editor for tiny bit of scripts. So here is my
>question: what is, for you, the current best ( but still kind of light!
>) Python editor/IDE ? A tiny precision, I am on Ubuntu so I am looking
>for a linux compatible editor.

I thought Ulipad WAS linux-compatible. Isn't it?

Dick Moores
XP, Python 2.5, editor is Ulipad



==
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Re: A problem with Time

[Dick Moores]

At 08:30 AM 8/16/2007, special_dragonfly wrote:
>Hello,
>
>I need to return the date yesterday in the form DDMM. I looked through
>the modules: time, datetime and calendar but can't find anything that leaps
>out at me.
>
>The problem I'm having is that although I can use time.localtime and get a
>tuple of the year, month, day and so forth, I don't believe I can just minus
>1 from the day, because I don't think it's cyclic, also, I can't see the
>date being linked in with the month.
>
>So is there any way of getting yesterdays date?

The question has already been well-answered, but since I've found 
using the datetime module to be tough going, I was wondering if 
either of these would be easier to understand and use:
1. <http://www.egenix.com/products/python/mxBase/mxDateTime/>
I see that mxDateTime comes with a 55-page manual as a PDF.

2. <http://labix.org/python-dateutil>

Dick Moores




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Re: 'REPL' style IDE

[Dick Moores]

At 10:50 AM 8/20/2007, beginner wrote:
>Hi Everyone,
>
>I am using the Wing IDE. It works great when developing applications,
>but the workflow is like Visual Studio -- after you execute it or
>debug it, the python script ends.
>
>What I want is an interactive interpreting environment. I want the IDE
>to execute a boot script to initialize my environment and create some
>basic data objects. And then I want to be able to type in command on
>the command line using these objects. The IDLE that comes with Python
>does this, but compared with Wing, it does not have a lot of the
>convenient features.
>
>I am wondering if there is anything more powerful than IDLE that can
>do this.

Are you sure you can't do this with Wing? Have you asked support, 
<[EMAIL PROTECTED]>?

Dick Moores



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Re: IDE for Python

[Dick Moores]

At 06:55 AM 8/21/2007, limodou wrote:
>On 8/21/07, king kikapu <[EMAIL PROTECTED]> wrote:
> > On Aug 21, 12:00 pm, Joel Andres Granados <[EMAIL PROTECTED]>
> > wrote:
> > > Hello list:
> > >
> > > I have tried various times to use an IDE for python put have always been
> > > disapointed.
> >
> >
> > I have also tried a lot of them (IDEs) in the last year. I was finally
> > happy with Eclipse/Pydev but i was always wanted a more "true" IDE for
> > Python.
> > I think i found it in Eric4 http://www.die-offenbachs.de/eric/index.html
> > You can download from here 
> http://www.riverbankcomputing.co.uk/pyqt/download.php
> > (binary installer for Windows that contains Eric and PyQt)
> > and have a look at it!
> >
>Maybe someone can try UliPad, I just release 3.7 version a few days before.

I'm a longtime, very satisfied Ulipad user, and heartily recommend 
Ulipad. <http://code.google.com/p/ulipad/>.

Limodou, although sometimes busy with other projects, is very 
responsive to requests for help with Ulilpad, and very open to 
suggestions for new features. He's Chinese, in Beijing, so is on 
Beijing time, but during his day he seems to check his mail often. 
(Gmail users can see when he's using his Gmail account.) If you do 
become a Ulipad user, I strongly suggest you subscribe to the Ulipad 
list at Google Groups, <http://groups.google.com/group/ulipad>.

Dick Moores
XP, Python 2.5, editor is Ulipad



>--
>I like python!
>UliPad <>: http://code.google.com/p/ulipad/
>My Blog: http://www.donews.net/limodou
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==
   Bagdad Weather
<http://weather.yahoo.com/forecast/IZXX0008_f.html> 

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Re: Speed of Python

[Dick Moores]

At 09:42 AM 9/7/2007, wang frank wrote:
>Are there any way to speed it up?

How about psyco?

Dick Moores
XP, Python 2.5.1, editor is Ulipad


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Re: number generator

[Dick Moores]

At 07:17 AM 3/9/2007, cesco wrote:
>On Mar 9, 3:51 pm, Paul Rubin <http://[EMAIL PROTECTED]> wrote:
> > "cesco" <[EMAIL PROTECTED]> writes:
> > > I have to generate a list of N random numbers (integer) whose sum is
> > > equal to M. If, for example, I have to generate 5 random numbers whose
> > > sum is 50 a possible solution could be [3, 11, 7, 22, 7]. Is there a
> > > simple pattern or function in Python to accomplish that?
> >
> > Erm, yes, lots of ways, there are probably further constraints on the
> > problem, such as the size of the integers, how the lists are supposed
> > to be distributed, etc.  Can you be more specific?  Is this for an
> > application?  If it's a homework problem, that's fine, but it's better
> > in that case for respondents to suggest hints rather than full solutions.
>
>Given two positive integers, N and M with N < M, I have to generate N
>positive integers such that sum(N)=M. No more constraints.

So why not just repeatedly call a function to generate lists of 
length N of random integers within the appropriate range (the closed 
interval [1,M-N-1]), and return the first list the sum of which is M? 
I don't understand what all the discussion is about. Time is not one 
of the constraints.

Dick Moores 

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Re: number generator

[Dick Moores]

At 06:38 AM 3/10/2007, Steven D'Aprano wrote:
>On Sat, 10 Mar 2007 02:32:21 -0800, Dick Moores wrote:
>
> > So why not just repeatedly call a function to generate lists of
> > length N of random integers within the appropriate range (the closed
> > interval [1,M-N-1]), and return the first list the sum of which is M?
> > I don't understand what all the discussion is about. Time is not one
> > of the constraints.
>
>Time is always a constraint. The sun will expand and destroy the Earth in
>a couple of billion years, it would be nice to have a solutions before
>then...
>
>*wink*
>
>Seriously, almost all programming problems have two implicit constraints:
>it must run as fast as practical, using as little computer resources (e.g.
>memory) as practical. Naturally those two constraints are usually in
>opposition, which leads to compromise algorithms that run "fast enough"
>without using "too much" memory.

OK, points well-taken.

The problem posed by the OP is "Given two positive integers, N and M 
with N < M, I have to generate N
positive integers such that sum(N)=M. No more constraints."

But let's say there is one more constraint--that for each n of the N 
positive integers, there must be an equal chance for n to be any of 
the integers between 1 and M-N+1, inclusive. Thus for M == 50 and N 
== 5, the generated list of 5 should be as likely to be [1,46,1,1,1] 
as [10,10,10,10,10] or [14, 2, 7, 1, 26].

Wouldn't sumRndInt() be THE solution?:
=
def sumRndInt(M, N):
 import random
 while True:
 lst = []
 for x in range(N):
 n = random.randint(1,M-N+1)
 lst.append(n)
 if sum(lst) == M:
 return lst

if __name__ == '__main__':

 N = 5
 M = 50

 lst = sumRndInt(M, N)

 print "N is %d, M is %d, lst is %s, sum(lst) is %d" % (N, M, 
lst, sum(lst))
==

I hope I don't seem querulous--I really want to know.

Thanks,

Dick Moores



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Re: number generator

[Dick Moores]

At 02:52 AM 3/13/2007, Duncan Booth wrote:
>Dick Moores <[EMAIL PROTECTED]> wrote:
>
> > But let's say there is one more constraint--that for each n of the N
> > positive integers, there must be an equal chance for n to be any of
> > the integers between 1 and M-N+1, inclusive. Thus for M == 50 and N
> >== 5, the generated list of 5 should be as likely to be [1,46,1,1,1]
> > as [10,10,10,10,10] or [14, 2, 7, 1, 26].
>
>I don't think what you wrote actually works. Any combination including a 46
>must also have four 1s, so the digit 1 has to be at least 4 times as likely
>to appear as the digit 46, and probably a lot more likely than that.

Yes, I see you're right. Thanks.

>On the other hand, making sure that each combination occurs equally often
>(as your example might imply) is doable but still leaves the question
>whether the order of the numbers matters: are [1,46,1,1,1] and [1,1,46,1,1]
>the same or different combinations?

If the added constraint is instead that the probability of generating 
a given list of length N be the same as that of generating any other 
list of length N, then I believe my function does the job. Of course, 
[1,46,1,1,1] and [1,1,46,1,1], as Python lists, are distinct. I ran 
this test for M == 8 and N == 4:
==
def sumRndInt(M, N):
 import random
 while True:
 lst = []
 for x in range(N):
 n = random.randint(1,M-N+1)
 lst.append(n)
 if sum(lst) == M:
 return lst

A = []
B = []
for x in range(10):
 lst = sumRndInt(8,4)
 if lst not in A:
 A.append(lst)
 B.append(1)
 else:
 i = A.index(lst)
 B[i] += 1

A.sort()
print A
print B
print len(A), len(B)
===
a typical run produced:
[[1, 1, 1, 5], [1, 1, 2, 4], [1, 1, 3, 3], [1, 1, 4, 2], [1, 1, 5, 
1], [1, 2, 1, 4], [1, 2, 2, 3], [1, 2, 3, 2], [1, 2, 4, 1], [1, 3, 1, 
3], [1, 3, 2, 2], [1, 3, 3, 1], [1, 4, 1, 2], [1, 4, 2, 1], [1, 5, 1, 
1], [2, 1, 1, 4], [2, 1, 2, 3], [2, 1, 3, 2], [2, 1, 4, 1], [2, 2, 1, 
3], [2, 2, 2, 2], [2, 2, 3, 1], [2, 3, 1, 2], [2, 3, 2, 1], [2, 4, 1, 
1], [3, 1, 1, 3], [3, 1, 2, 2], [3, 1, 3, 1], [3, 2, 1, 2], [3, 2, 2, 
1], [3, 3, 1, 1], [4, 1, 1, 2], [4, 1, 2, 1], [4, 2, 1, 1], [5, 1, 1, 1]]

[2929, 2847, 2806, 2873, 2887, 2856, 2854, 2825, 2847, 2926, 2927, 
2816, 2816, 2861, 2919, 2820, 2890, 2848, 2898, 2883, 2820, 2820, 
2829, 2883, 2873, 2874, 2891, 2884, 2837, 2853, 2759, 2761, 2766, 2947, 2875]

35 35

Dick Moores




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Re: number generator

[Dick Moores]

At 06:59 AM 3/13/2007, Anton Vredegoor wrote:
>Dick Moores wrote:
>
> > If the added constraint is instead that the probability of generating
> > a given list of length N be the same as that of generating any other
> > list of length N, then I believe my function does the job. Of course,
> > [1,46,1,1,1] and [1,1,46,1,1], as Python lists, are distinct. I ran
> > this test for M == 8 and N == 4:
>
>Yes, I believe your function is OK. But the 'fencepost' method posted
>earlier in this thread also does this and it's faster AND it's only two
>line of code ...

Yes, I tested that after posting mine. Paul Rubin's fencepost method 
is about 14 times faster than mine for the same M == 8 and N == 4!  :(

> > A = []
> > B = []
> > for x in range(10):
> >  lst = sumRndInt(8,4)
> >  if lst not in A:
> >  A.append(lst)
> >  B.append(1)
> >  else:
> >  i = A.index(lst)
> >  B[i] += 1
> >
> > A.sort()
>
>Doesn't sorting break the correspondence between A and B?

Yes, but I thought that it would be easier to see that all the 
permutations are represented. It seemed clear enough that with larger 
num, all counts would approach num/35..

>  Also, a more
>pythonic way to count would be to convert the lst into a tuple and then
>do something with a dictionary. Dictionaries have faster lookup. For
>example:
>
>T = tuple(lst)
>D[T] = D.get(T,0) + 1
>
>in the loop in order to count the occurrences.

Sorry, I don't understand this. Could you spell it out for me by 
rewriting my above test to use it? Thanks!

Dick Moores


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Re: number generator

[Dick Moores]

At 05:47 PM 3/10/2007, Paul Rubin wrote:

>The fencepost method still seems to be simplest:
>
> t = sorted(random.sample(xrange(1,50), 4))
> print [(j-i) for i,j in zip([0]+t, t+[50])]

=
M = 50
N = 4
def sumRndIntRubin(M, N):
 import random
 t = sorted(random.sample(xrange(1,M), N-1))
 lst = [(j-i) for i,j in zip([0]+t, t+[M])]

 print t
 print t + [M]
 print [0] + t
 print lst
 print sum(lst)

sumRndIntRubin(M, N)

[6, 20, 31]
[6, 20, 31, 50]
[0, 6, 20, 31]
[6, 14, 11, 19]
50

I understand what zip() and random.sample() are doing, and the above 
helps me get inside the fencepost method, but I don't understand WHY 
it works, or how in the world anyone could have devised it. It is 
truly magical to me!

BTW I did see this in this thread, "Suppose you have a fixed 
telegraph pole at N and a fixed telegraph pole at M, and you're given 
5 more telegraph poles..." (Gerard Flanagan), but even now I can't 
take it anywhere. I guess I'm just a dim bulb. (I thought I was a 
fairly smart guy until I took up Python.)

Dick Moores

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Re: number generator

[Dick Moores]

At 06:20 PM 3/13/2007, Paul Rubin wrote:
>Dick Moores <[EMAIL PROTECTED]> writes:
> > I understand what zip() and random.sample() are doing, and the above
> > helps me get inside the fencepost method, but I don't understand WHY
> > it works, or how in the world anyone could have devised it. It is
> > truly magical to me!
>
>It's Gerald Flanagan's telegraph pole method that you quoted (I
>misremembered it as "fencepost"):
>
> "Suppose you have a fixed telegraph pole at N and a fixed telegraph
> pole at M, and you're given 5 more telegraph poles..." (Gerard Flanagan),
>
>Consider this diagram for the numbers from 1 to 50:
>
>   |--|
>
>The vertical bar at the left represents 0 and the vertical bar
>at the right represents 51.  The fifty dashes represent 1,2,3...50.
>You can also view the fifty dashes as a line segment of length 50.
>
>The fencepost method is to simply chop the line segment into smaller
>pieces.  You do that by choosing some random points inside the segment:
>
> >>> import random
> >>> random.sample(xrange(1,50), 4)
> [49, 37, 22, 5]
>
>so mark those points with plus signs (let's see if I got this right)
>and label the points from left to right, calling them p0,p1,p2,p3:
>
> |++--+---+-|
>  p0   p1 p2  p3
>
>So the length of the leftmost small segment is p0-0, the length of the
>second segment is p1-p0, the third is p2-p1, the fourth is p3-p2, and
>the fifth is 50-p3.  So those lengths are the numbers you want.
>
>The zip thing was just a way to avoid using messy subscripts to
>compute the lengths.  Another way to do it is (untested):
>
>t2 = [0] + t + [50]
>lst = [(t2[i] - t2[i-1]) for i in xrange(1, len(t2))]

Works fine!

>I'm not sure which is better from a Python stylistic perspective.

I'm not sure, but I think if you had written it this way at first, I 
would have understood it.  But I'm glad to have learned the zip way!

>Using zip that way is fairly natural in Haskell, which I've been
>fooling around with lately.  All you're doing is subtracting adjacent
>elements by making two versions of the list, one of them shifted over
>one place, then subtracting element by element, instead of jumping
>around inside a single list, with more ways to make off-by-one errors.
>It looked more symmetrical in the Python code so I did it that way.

Thank you, thank you! You've made it very clear up to this point. 
I'll worry about the Haskell approach later, much later. ;)

Dick Moores

>FWIW, the actual Haskell approach would translate to something more like:
>
>from itertools import chain, izip
>lst = [(j-i) for i,j in izip(chain([0],t), chain(t,[50]))]
>
>which avoids making the intermediate zipped list.


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Re: Weekly Python Patch/Bug Summary

[Dick Moores]

May I ask a dumb question here? It isn't clear to me what to do with
these patches. For most of them there is something like, "Committed
as r54386 and r54387". I'm familiar with updating the editor Ulipad
to the latest revision, using software such as TortoiseSVN and RapidSVN.
Is that what is meant? And if so, what's the URL of the trunk?
Thanks,
Dick Moores




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Re: Weekly Python Patch/Bug Summary

[Dick Moores]

At 01:32 AM 3/17/2007, Terry Reedy wrote:

>"Dick Moores" <[EMAIL PROTECTED]> wrote in message
>news:[EMAIL PROTECTED]
>| May I ask a dumb question here? It isn't clear to me what to do with
>these patches. For most of them there is something like, "Committed as
>r54386 and r54387". I'm familiar with updating the editor Ulipad to the
>latest revision, using software such as TortoiseSVN and RapidSVN. Is that
>what is meant? And if so, what's the URL of the trunk?
>-
>
>Yes, those are svn revision numbers.  Start at svn.python.org.

I thought I'd give 
<http://svn.python.org/projects/python/branches/release25-maint/> 
(the latest release (plus bug fixes) of Python) a try. I first backed 
up my Python25 folder (I'm using Win XP). Then with Python 25 open I 
opened the Explorer context menu for the folder and then the 
TortoiseSVN sub-menu. There doesn't seem to have a menu item that 
will enable me to update. I tried Export... and entered 
<http://svn.python.org/projects/python/branches/release25-maint/> as 
"URL of repository", but that choice seems to expect the Python25 
folder to be empty. Can you tell me what to do to just update?

Dick 

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Re: SPE question

[Dick Moores]

At 01:39 AM 3/27/2007, alain wrote:
>Hi,
>
>Could someone tell me how to uninstall SPE under windows?

Well, mine is in E:\Python25\Lib\site-packages\_spe, so I'd try 
deleting that folder.

Dick Moores 

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Re: SPE question

[Dick Moores]

At 03:37 AM 3/27/2007, [EMAIL PROTECTED] wrote:
>On Mar 27, 11:39 am, "alain" <[EMAIL PROTECTED]> wrote:
> > Hi,
> >
> > Could someone tell me how to uninstall SPE under windows?
> >
> > Alain
>
>Dunno about SPE, but most Python modules I've installed can
>be uninstalled from control panel/add remove programs.

SPE doesn't show up on my win XP add/remove programs list.

Dick Moores


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Welch essential for learning Tkinter well?

[Dick Moores]

In a couple of places recently I've seen Brent Welch's _Practical 
Programming in Tcl & Tk_ (<http://tinyurl.com/ynlk8b>) recommended 
for learning Tkinter well.

So a couple of questions:

1) Is it really good for learning Tkinter, even though it doesn't 
mention Tkinter at all (in the 4th edition at least)?

2) If it is good for learning Tkinter, can I get by with a cheaper, 
used copy of the 3rd edition?

Thanks,

Dick Moores

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Re: Welch essential for learning Tkinter well?

[Dick Moores]

At 10:36 AM 4/6/2007, Russell E. Owen wrote:
>In article <[EMAIL PROTECTED]>,
>  Kevin Walzer <[EMAIL PROTECTED]> wrote:
>
> > James Stroud wrote:
> > >This begs the
> > > question, is anyone truly an expert in Tkinter?
> >
> > Frederick Lundh is, if anyone is.
> >
> > http://www.pythonware.com/library/tkinter/introduction/index.htm (outdated)
> > http://effbot.org/tkinterbook/ (new but incomplete)
>
>I agree that this is an excellent resource.
>
>I find Welch's book and the on-line tcl/tk help very helpful for Tkinter
>programming--especially some of the more obscure details. But to use
>either of these resources comfortably you must learn the basics of
>Tkinter first (including understanding the simple mapping between
>Tkinter and Tcl/Tk).

Where can I get this mapping spelled out?

>For learning the basics of Tkinter I suggest the links that Kevin listed
>above and/or Alex Martelli's "Python in a Nutshell" (an excellent
>reference in any case).

Although owning the 2nd ed. of "Python is a Nutshell", I hadn't 
thought of looking into it for Tkinker. There's a whole chapter, 
"Tkinter GUIs" (46 pages!).

>  Grayson's book is another reasonable alternative
>(and includes enough reference material to keep you from having to refer
>to the tcl/tk documentation very often).

One web tutorial that looks good to me is "Thinking in Tkinter", by 
Stephen Ferg (<http://www.ferg.org/thinking_in_tkinter/index.html>).

My thanks to all who responded.

Dick Moores


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Saving output of Turtle Graphics?

[Dick Moores]

I accidentally stumbled across the Turtle Graphics module (turtle.py) 
the other day and have been having some fun with it.

Now I'm wondering if there is a way to build into a script the saving 
of each window just before it is cleared. For example, here are a 
couple that I've saved by screen capture:
<http://www.rcblue.com/Misc/RandomTriangles.jpg>
<http://www.rcblue.com/Misc/RandomTriangles2.jpg>

They were produced by this script:

=
# randomTriangles.py

import turtle as T
from random import *

def twoRndN(low=0, high=1):
 """
 generate two random floats x, y in the range [low, high) such that x <= y
 """
 x, y = uniform(low, high), uniform(low, high)
 if x <= y:
 return x, y
 else:
 return y, x

T.setup(width=1000, height=700, startx=0, starty=0)
T.title("Random Triangles with random R,G,B")

colorRange = "all"
if colorRange == "random":
 lowR, highR = twoRndN()
 lowG, highG = twoRndN()
 lowB, highB = twoRndN()

count = 0
for n in range(300):
 wdth = randrange(0,7,3)
 T.width(wdth)
 T.speed("fastest")
 if colorRange == "dark":
 R = uniform(.1, .5)
 G = uniform(.1, .5)
 B = uniform(.1, .5)
 elif colorRange == "pastel":
 R = uniform(.5, .9)
 G = uniform(.5, .9)
 B = uniform(.5, .9)
 elif colorRange == "all":
 R = uniform(0, 1)
 G = uniform(0, 1)
 B = uniform(0, 1)
 # set RGB for one color of your choice
 elif colorRange == "manual":
 R = .45
 G = .2
 B = .2
 elif colorRange == "random":
 R = uniform(lowR, highR)
 G = uniform(lowG, highG)
 B = uniform(lowB, highB)

 T.color(R,G,B)
 T.begin_fill()
 # 2 connected lines will fill as a triangle
 for x in range(2):
 coord = (randint(-500,500), randint(-350,350))
 T.goto(coord)
 T.end_fill()

 count += 1
 if count > 5:
 clr = randint(0,5)
 if clr == 0:
 T.clear()
 count = 0
T.done()
==
(The docs for Turtle graphics for Tk are at 
<http://www.python.org/doc/2.5/lib/module-turtle.html>)

But how could I have saved them "automatically"?

The script as shown will clear (T.clear() -- the 3rd line from the 
bottom) the window after producing 6 to maybe 15 superimposed 
triangles, so clearing will take place maybe 30 times. How can I save 
as images each of the 30 windows just before they are cleared?

Thanks,

Dick Moores

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Re: Welch essential for learning Tkinter well?

[Dick Moores]

At 03:43 AM 4/7/2007, James Stroud wrote:
>Dick Moores wrote:
> > At 10:36 AM 4/6/2007, Russell E. Owen wrote:
> >> I find Welch's book and the on-line tcl/tk help very helpful for Tkinter
> >> programming--especially some of the more obscure details. But to use
> >> either of these resources comfortably you must learn the basics of
> >> Tkinter first (including understanding the simple mapping between
> >> Tkinter and Tcl/Tk).
> >
> > Where can I get this mapping spelled out?
>
>Grayson Appendix A. $25 pdf--well worth it in your time.

Terrific! Thank you.

Dick

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Re: Saving output of Turtle Graphics?

[Dick Moores]

At 06:50 AM 4/7/2007, =?ISO-8859-2?Q?Wojciech_Mu=B3a?= wrote:
>Dick Moores wrote:
> > I accidentally stumbled across the Turtle Graphics module (turtle.py)
> > the other day and have been having some fun with it.
> >
> > Now I'm wondering if there is a way to build into a script the saving of
> > each window just before it is cleared. For example, here are a couple
> > that I've saved by screen capture:
> > <http://www.rcblue.com/Misc/RandomTriangles.jpg>
> > <http://www.rcblue.com/Misc/RandomTriangles2.jpg>
>
>Turtle module uses Tk canvas element to draw graphics ('_canvas'
>attribute). I've written module, that exports canvas graphics to SVG
>file: http://wmula.republika.pl/proj/canvas2svg/ -- it may be useful
>for you.

I afraid I'm totally unfamiliar with SVG. Would it be possible for 
you or someone else on the list to show how to use your module to 
export the simple product of this simple script to an SVG file?

===
import turtle as T
from random import randint
T.setup(width=1000, height=700, startx=0, starty=0)
T.color(1, .5, .5)
T.begin_fill()
# 2 connected lines will fill as a triangle
for x in range(2):
 coord = (randint(-500,500), randint(-350,350))
 T.goto(coord)
T.end_fill()

T.done()


Thanks,

Dick Moores
Win XP Pro SP2
Python 2.5
Python IDE: Ulipad 3.6


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Re: Saving output of Turtle Graphics?

[Dick Moores]

At 08:48 AM 4/7/2007, =?ISO-8859-2?Q?Wojciech_Mu=B3a?= wrote:
>Dick Moores wrote:
> >> Turtle module uses Tk canvas element to draw graphics ('_canvas'
> >> attribute). I've written module, that exports canvas graphics to SVG
> >> file: http://wmula.republika.pl/proj/canvas2svg/ -- it may be useful
> >> for you.
> >
> > I afraid I'm totally unfamiliar with SVG. Would it be possible for you
> > or someone else on the list to show how to use your module to export the
> > simple product of this simple script to an SVG file?
> >
> > ===
> > import turtle as T
>import canvasvg
> > from random import randint
> > T.setup(width=1000, height=700, startx=0, starty=0)
> > T.color(1, .5, .5)
> > T.begin_fill()
> > # 2 connected lines will fill as a triangle
> > for x in range(2):
> > coord = (randint(-500,500), randint(-350,350))
> > T.goto(coord)
> > T.end_fill()
>
>canvasvg.saveall("image.svg", T._canvas)
>
> > T.done()
> > 

OK, thanks, now I've got

===
http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd'>http://www.w3.org/2000/svg";>


What do I do to see this?

Dick

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Re: Saving output of Turtle Graphics?

[Dick Moores]

At 09:31 AM 4/7/2007, =?ISO-8859-2?Q?Wojciech_Mu=B3a?= wrote:
>Dick Moores wrote:
> > What do I do to see this?
>
>For example Opera 9 and Firefox 1.5+ are able to view SVG files;
>there is a free plugin for IrfanView.

Ha. I had tried it with Firefox 2 already, but I stupidly changed the 
extension to HTM first. I'll also get the IrfanView plugin.

Thanks for all the help, and especially for your canvasvg.py module.

Dick


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Where's the Starship's crew?

[Dick Moores]

<http://starship.python.net/crew/index.html>

I didn't check on all of them, but the only one I found was Mark 
Hammond <http://starship.python.net/crew/mhammond/>.

Dick Moores

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Re: Where's the Starship's crew?

[Dick Moores]

At 04:54 AM 10/5/2007, Thomas Heller wrote:
>Dick Moores schrieb:
> > <http://starship.python.net/crew/index.html>
> >
> > I didn't check on all of them, but the only one I found was Mark
> > Hammond <http://starship.python.net/crew/mhammond/>.
> >
> > Dick Moores
> >
>
>There are more. Think of it as a game you have to solve.

Yeah, a mind numbing game!

http://starship.python.net/crew/ewalstad/ Eric Walstad
http://starship.python.net/crew/piers/ Piers Lauder
http://starship.python.net/crew/jae/ --> http://zhar.net/  John Eikenberry
http://starship.python.net/crew/mwh/
http://starship.python.net/crew/manus/ Manus Hand
http://starship.python.net/crew/bhoel/ Berthold Höllmann
http://starship.python.net/crew/marduk/ ("Server Error")
http://starship.python.net/crew/schorsch/
http://starship.python.net/crew/dni/ David Niergarth
http://starship.python.net/crew/jcooley/ James Cooley
http://starship.python.net/crew/sdrees/ Stefan Drees
http://starship.python.net/crew/jwt/ Jim Tittsler
http://starship.python.net/crew/theller/ Thomas Heller
http://starship.python.net/crew/gherman/ Dinu Gherman
http://starship.python.net/crew/mhammond/ Mark Hammond
http://starship.python.net/crew/atuining/
http://starship.python.net/crew/hooft/ Rob W.W. Hooft
http://starship.python.net/crew/lemburg/ --> http://www.egenix.com/
http://starship.python.net/crew/goodger/ David Goodger
http://starship.python.net/crew/mmuller/ Mike Muller
http://starship.python.net/crew/skippy/ same as 
http://starship.python.net/crew/mhammond/ Mark Hammond

BTW How could I have done this with Python script?

Dick Moores

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Top Programming Languages of 2013

[Dick Moores]

<http://www.redcanary.ca/view/top-programming>

Dick Moores

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Using msvcrt (in Windows), how to catch Enter key?

[Dick Moores]

Windows XP Pro, Python 2.5.1

import msvcrt
while True:
 if msvcrt.kbhit():
 key = msvcrt.getch()
 if key == 'Enter'
 do something

Is there a way to catch the pressing of the 'Enter' key?

Thanks,

Dick Moores

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Re: Using msvcrt (in Windows), how to catch Enter key?

[Dick Moores]

At 04:29 AM 10/29/2007, Filip Wasilewski wrote:
>On Oct 29, 11:26 am, Dick Moores <[EMAIL PROTECTED]> wrote:
> > Windows XP Pro, Python 2.5.1
> >
> > import msvcrt
> > while True:
> >  if msvcrt.kbhit():
> >  key = msvcrt.getch()
> >  if key == 'Enter'
> >  do something
> >
> > Is there a way to catch the pressing of the 'Enter' key?
>
>Yes there is. Just open the Python shell and see what is being
>returned by `getch` or `getche` functions when you press Enter:
>
> >>> import msvcrt
> >>> msvcrt.getch()
>'\r'

Terrific! Thanks.

>Also try to avoid `busy waiting` and calling msvcrt.kbhit in a loop
>without a sleep statement.
>I don't know your case but probably this
>should be enough:
>
>while True:
> if msvcrt.getch() == '\r':

I tried it and find that without the msvcrt.kbhit the first key I hit 
doesn't do anything. I have to hit that key again, or another key.

Dick

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Re: Using msvcrt (in Windows), how to catch Enter key?

[Dick Moores]

At 09:53 AM 10/29/2007, Dick Moores wrote:
>At 09:26 AM 10/29/2007, Gabriel Genellina wrote:
> >On 29 oct, 09:23, Dick Moores <[EMAIL PROTECTED]> wrote:
> >
> > > >while True:
> > > > if msvcrt.getch() == '\r':
> > >
> > > I tried it and find that without the msvcrt.kbhit the first key I hit
> > > doesn't do anything. I have to hit that key again, or another key.
> >
> >I'd say there is a logic error in your program then; keys don't "do
> >anything" by themselves.
> >Try posting a small sample, telling what you get and what you expect.
>
>Huh. Works now.
>
>import msvcrt
>while True:
>  key = msvcrt.getch()
>  if key == 'h':
>  print 'Hello'
>  if key == 'b':
>  print 'Bye'
>  if key == '\r': # 'Enter' key
>  break
>
>Dick

But here's a case where it seems I do need the

if msvcrt.kbhit() line

=
#!/usr/bin/env python
#coding=utf-8
import time
import msvcrt
timeNow = time.time()
oldTimeNow = timeNow
while True:
 if msvcrt.kbhit():
 key = msvcrt.getch()
 if key == 'h':
 print 'Hello'
 if key == 'b':
 print 'Bye'
 if key == '\r': # Enter key
 break
 timeNow = time.time()
 if timeNow - oldTimeNow > 5:
 print "5 seconds passed"
 oldTimeNow = timeNow
==

Without that line:
==
#!/usr/bin/env python
#coding=utf-8
import time
import msvcrt
timeNow = time.time()
oldTimeNow = timeNow
while True:
 #if msvcrt.kbhit():
 key = msvcrt.getch()
 if key == 'h':
 print 'Hello'
 if key == 'b':
 print 'Bye'
 if key == '\r': # Enter key
 break
 timeNow = time.time()
 if timeNow - oldTimeNow > 5:
 print "5 seconds passed"
 oldTimeNow = timeNow


Without that line the "5 seconds passed" report is printed ONLY after 
a "b" or an "h", not what I want.

Dick

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Re: Using msvcrt (in Windows), how to catch Enter key?

[Dick Moores]

At 09:26 AM 10/29/2007, Gabriel Genellina wrote:
>On 29 oct, 09:23, Dick Moores <[EMAIL PROTECTED]> wrote:
>
> > >while True:
> > > if msvcrt.getch() == '\r':
> >
> > I tried it and find that without the msvcrt.kbhit the first key I hit
> > doesn't do anything. I have to hit that key again, or another key.
>
>I'd say there is a logic error in your program then; keys don't "do
>anything" by themselves.
>Try posting a small sample, telling what you get and what you expect.

Huh. Works now.

import msvcrt
while True:
 key = msvcrt.getch()
 if key == 'h':
 print 'Hello'
 if key == 'b':
 print 'Bye'
 if key == '\r': # 'Enter' key
 break

Dick 

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Re: Using msvcrt (in Windows), how to catch Enter key?

[Dick Moores]

Reposting, deleting the [Possible SPAM] from the Subject: header.

At 03:23 PM 10/29/2007, Gabriel Genellina wrote:
 >En Mon, 29 Oct 2007 14:39:49 -0300, Dick Moores <[EMAIL PROTECTED]> escribió:
 >
 > > But here's a case where it seems I do need the
 > >
 > > if msvcrt.kbhit() line
 >
 >At least add a small sleep() call inside the loop, to be nice to other
 >running processes:
 >
 > > =
 > > #!/usr/bin/env python
 > > #coding=utf-8
 > > import time
 > > import msvcrt
 > > timeNow = time.time()
 > > oldTimeNow = timeNow
 > > while True:
 > >  if msvcrt.kbhit():
 > >  key = msvcrt.getch()
 > >  if key == 'h':
 > >  print 'Hello'
 > >  if key == 'b':
 > >  print 'Bye'
 > >  if key == '\r': # Enter key
 > >  break
 > else:
 > time.sleep(0.1)
 > >  timeNow = time.time()
 > >  if timeNow - oldTimeNow > 5:
 > >  print "5 seconds passed"
 > >  oldTimeNow = timeNow
 > > =

Yes, that makes a major difference in the CPU
usage percentage on my computer. In fact I can't
even tell that there is anything going on other
than the usual behind-the-scenes XP stuff. CPU
usage stays right around 0% or 6%, with an
occasional 6% and a very occasional 15%.
Interestingly, sleep(0.001) makes as big a
difference as your sleep(0.1), but sleep(0.0001) bumps it up to a steady 100%!

Thanks,

Dick 

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Re: [Possible SPAM] Re: Using msvcrt (in Windows), how to catch Enter key?

[Dick Moores]

At 03:23 PM 10/29/2007, Gabriel Genellina wrote:
>En Mon, 29 Oct 2007 14:39:49 -0300, Dick Moores <[EMAIL PROTECTED]> escribió:
>
> > But here's a case where it seems I do need the
> >
> > if msvcrt.kbhit() line
>
>At least add a small sleep() call inside the loop, to be nice to other
>running processes:
>
> > =
> > #!/usr/bin/env python
> > #coding=utf-8
> > import time
> > import msvcrt
> > timeNow = time.time()
> > oldTimeNow = timeNow
> > while True:
> >  if msvcrt.kbhit():
> >  key = msvcrt.getch()
> >  if key == 'h':
> >  print 'Hello'
> >  if key == 'b':
> >  print 'Bye'
> >  if key == '\r': # Enter key
> >  break
> else:
> time.sleep(0.1)
> >  timeNow = time.time()
> >  if timeNow - oldTimeNow > 5:
> >  print "5 seconds passed"
> >  oldTimeNow = timeNow
> > =

Yes, that makes a major difference in the CPU 
usage percentage on my computer. In fact I can't 
even tell that there is anything going on other 
than the usual behind-the-scenes XP stuff. CPU 
usage stays right around 0% or 6%, with an 
occasional 6% and a very occasional 15%. 
Interestingly, sleep(0.001) makes as big a 
difference as your sleep(0.1), but sleep(0.0001) bumps it up to a steady 100%!

Thanks,

Dick 

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Re: Using msvcrt (in Windows), how to catch Enter key?

[Dick Moores]

At 06:34 PM 10/29/2007, Gabriel Genellina wrote:
>En Mon, 29 Oct 2007 21:22:36 -0300, Dick Moores <[EMAIL PROTECTED]> escribió:
>
> > At 03:23 PM 10/29/2007, Gabriel Genellina wrote:
> >> En Mon, 29 Oct 2007 14:39:49 -0300, Dick Moores <[EMAIL PROTECTED]>
> >> escribió:
> >>
> >>
> >> At least add a small sleep() call inside the loop, to be nice to other
> >> running processes:
> >>
> >
> > Yes, that makes a major difference in the CPU
> > usage percentage on my computer. In fact I can't
> > even tell that there is anything going on other
> > than the usual behind-the-scenes XP stuff. CPU
> > usage stays right around 0% or 6%, with an
> > occasional 6% and a very occasional 15%.
> > Interestingly, sleep(0.001) makes as big a
> > difference as your sleep(0.1), but sleep(0.0001) bumps it up to a steady
> > 100%!
>
>The underlying function in Windows is Sleep (or SleepEx) which takes an
>argument in milliseconds. 0.0001s = 0.1ms and it's rounded to 0. Sleep(0)
>has very specific semantics - for a single threaded program, it does
>nothing, so your code is effectively a busy loop taking 100% CPU.

Ah, useful information. Thank you. Where'd you learn that?

Dick Moores


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Re: What happened to SPE?

[Dick Moores]

At 07:43 AM 1/11/2007, Paulo Pinto wrote:
>does anyone know what happened to SPE?
>
>It seems that the address http://pythonide.stani.be
>is no longer valid. :(

I'd suggest subscribing to the Python-spe-users list, 
<https://lists.berlios.de/mailman/listinfo/python-spe-users>, or 
reading the archive there.

Dick Moores



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Python 2.5 Quick Reference

[Dick Moores]

<http://rgruet.free.fr/PQR25/PQR2.5.html>
Is this reliable? (Looks good to me, but...)

Thanks,

Dick Moores


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Re: Python 2.5 Quick Reference

[Dick Moores]

At 04:02 AM 2/3/2007, Robin Becker wrote:
>Dick Moores wrote:
> > <http://rgruet.free.fr/PQR25/PQR2.5.html>
> > Is this reliable? (Looks good to me, but...)
> >
>.
>
>I really like these for a good overview

So it looks accurate?

Dick Moores

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Definitions of editor and IDE?

[Dick Moores]

Are there generally accepted definitions of "editor" and
"IDE". Is there a clear-cut distinction between them? I've been
looking at the lists of each at python.org,
<
http://wiki.python.org/moin/PythonEditors>  and
<
http://wiki.python.org/moin/IntegratedDevelopmentEnvironments>.
Many programs are on both lists: Komodo, Eclipse, jedit, SPE, Wing IDE,
UliPad, etc.
Dick Moores



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Unicode is confusing me

[Dick Moores]

As per p. 188 of Python for Dummies, I've created a sitecustomize.py
in  my site-packages directory:


# sitecustomize.py  (see p.188 of Python for Dummies)
import sys
sys.setdefaultencoding('utf-8')
===

With that in place, at the interactive prompt this goes well:
===
>>> import sys
>>> sys.getdefaultencoding()
'utf-8'
>>> a = [u'\u91cd', u'\u8981', u'\u6027']
>>>for x in range(3):
. . .   print a[x],
. . .
重 要 性
>>>
===
The 3 CJK characters are printed very nicely.

However, when I put the last 3 lines of that code in a script,


a = [u'\u91cd', u'\u8981', u'\u6027']
for x in range(3):
print a[x]
===

and redirect the output to a text file, I get
"Traceback (most recent call last):
  File "E:\Python25\dev\Untitled1.py", line 3, in ?
print a[x]
UnicodeEncodeError: 'ascii' codec can't encode character u'\u91cd' in
position 0: ordinal not in range(128)"

I thought maybe it would help if I made the first line,
# -*- coding: utf-8 -*-

but that made no difference. Got the same error.

Can someone help me understand what's going on?

Thanks,

Dick Moores
-- 
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Win XP Pro SP2
Python 2.5
wxPython 2.8.1.1 Unicode
Python IDE: Ulipad 3.6
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Re: Unicode is confusing me

[Dick Moores]

I'm the OP, and answering my own question. I received excellent advice
from the developer of Ulipad, Limodou.

On 2/10/07, Dick Moores <[EMAIL PROTECTED]> wrote:

> 
> a = [u'\u91cd', u'\u8981', u'\u6027']
> for x in range(3):
> print a[x]
> ===

The script should be
===
# -*- coding: utf-8 -*-
a = [u'\u91cd', u'\u8981', u'\u6027']
for x in range(3):
   print a[x].encode('utf-8'),

When output is redirected to a text file, this give a very pretty
重 要 性

Also, it turns out that I didn't need that sitecustomize.py .

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Win XP Pro SP2
Python 2.5
wxPython 2.8.1.1 Unicode
Python IDE: Ulipad 3.6
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Re: favourite editor

[Dick Moores]

At 08:41 PM 2/10/2007, azrael wrote:
>Since i'm new on this forum, and first time meeting a python comunity,
>i wanted to ask you for your python editors.
>
>Im looking for some good python editor, with integrated run function,
>without having to set it up manualy like komodo.
>I found the pyscripter, and it has all i need, but it's unsatble.
>bloated. it crashes when i close an yplication window run by python
>from pyscripter. please. tell me a good one with buil in run (<-very
>important) and nice gui. if possible to suport projects, code
>highlighting, code completition, class browser, python comand line
>(>>>), traceback.

UliPad. <http://wiki.woodpecker.org.cn/moin/UliPad>

Dick Moores

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mpmath puzzle

[Dick Moores]

For 1234 ** 10.9, why the wrong result from mpmath.power()?


#!/usr/bin/env python
#coding=utf-8
from mpmath import *

mpf.dps = 32

x = mpf(1234)
y = mpf(10.9)

print power(x,y)
print "4.9583278648155041477415234438717e+33" # from Windows calculator

"""
output:
4.9583278648155166864966558721921e+33
4.9583278648155041477415234438717e+33
"""

(Code is also at <http://python.pastebin.com/m72a277b8>)

Thanks,

Dick Moores

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Help with sympy, please

[Dick Moores]

from __future__ import division
Here's what I'm trying to do, but using sympy:
=
from math import e
n = 1
prod = 1
k = 0
while k < 1000:
 k += 1
 term = (e**(1.0/n))/(e**(1.0/(n+1)))
 prod *= term
 n += 2
print prod, term

Output:
1.99950018746 1.0025013  (the limit is 2)



from sympy import *
from sympy import Rational as R
from sympy.numerics import *

prec = 50
Float.setdps(prec)
e = evalf(E)
n = 1
k = 0
prod = evalf(R(1,1))
while k < 1000:
 k += 1
 n = evalf(R(n,1))
 term = (e**(1/n))/(e**(1/(n+1)))
 prod *= term
 n += 2
print prod, term
===

This gets:
Traceback (most recent call last):
   File "E:\PythonWork\Untitled 5.py", line 20, in 
 term = (e**(1/n))/(e**(1/(n+1)))
TypeError: unsupported operand type(s) for /: 'int' and 'Float'

Thanks,

Dick Moores

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Re: Help with sympy, please

[Dick Moores]

At 03:42 PM 11/18/2007, Dennis Lee Bieber wrote:
>On Sun, 18 Nov 2007 13:02:01 -0800, Dick Moores <[EMAIL PROTECTED]>
>declaimed the following in comp.lang.python:
>
> >
> > This gets:
> > Traceback (most recent call last):
> >File "E:\PythonWork\Untitled 5.py", line 20, in 
> >  term = (e**(1/n))/(e**(1/(n+1)))
> > TypeError: unsupported operand type(s) for /: 'int' and 'Float'
> >
> Seems self-explanatory... try using 1.0 rather than 1

term = (e**(1.0/n))/(e**(1.0/(n+1)))
TypeError: unsupported operand type(s) for /: 'float' and 'Float'

Dick 

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Re: Help with sympy, please

[Dick Moores]

At 04:26 PM 11/18/2007, Fredrik Johansson wrote:
>On Nov 19, 2007 1:05 AM, Dick Moores <[EMAIL PROTECTED]> wrote:
>Hi Dick, I recognize you from python-list, where you had a question
>about mpmath.
>
>Your code still won't work if you convert the numbers to Floats
>because the Float type in sympy.numerics does not implement ** for
>fractional numbers. You could use the exp function in
>sympy.numerics.functions instead to compute e**x.

Thanks, Fredrik, but I get the same error using either exp or power:

from __future__ import division
from sympy import *
from sympy import Rational as R
from sympy.numerics import *
from sympy.numerics.functions import power, exp

prec = 50
Float.setdps(prec)
e = evalf(E)
n = 1
m = n + 1
k = 0
n = evalf(R(n,1))
m = evalf(R(m,1))
prod = evalf(R(1,1))
prec = 50
Float.setdps(prec)
e = evalf(E)
n = 1
k = 0
prod = evalf(R(1,1))
while k < 1000:
  k += 1
  n = evalf(R(n,1))
  term = (exp(1/n))/(exp(1/(n+1)))
  prod *= term
  n += 2
print prod, term
=
term = (exp(1/n))/(exp(1/(n+1)))
TypeError: unsupported operand type(s) for /: 'int' and 'Float'

And also if I use sympy.numerics.functions.power in that line, as
term = power(e,(1/n))/power(e,(1/(n+1)))

I get:

term = power(e,(1/n))/power(e,(1/(n+1)))
TypeError: unsupported operand type(s) for /: 'int' and 'Float'

Dick


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Re: Help with sympy, please

[Dick Moores]

At 04:26 PM 11/18/2007, Fredrik Johansson wrote:

>Basically, sympy.numerics is an old version of mpmath. The
>sympy.numerics module is not very well integrated in SymPy, slower
>than mpmath, and has a couple bugs that have subsequently been fixed
>in mpmath. In sympycore (http://code.google.com/p/sympycore/), we're
>using the latest version of mpmath and integrating it directly into
>the symbolic engine; it will be much more robust and user-friendly. It
>will hopefully not be long until we merge the improvements we've done
>in the sympycore project with the main SymPy branch.
>
>Fredrik

OK, I tried mpmath again, and to my surprise, it went well!

===
#!/usr/bin/env python
#coding=utf-8
from mpmath import *
mpf.dps = 50
n = 1
k = 0
prod = mpf(1)
while k < 10:
 k += 1
 term = exp(1.0/n)/exp(1.0/(n+1))
 prod *= term
 n += 2
print prod, term
==
Output:
1.95187499635016028080844735182389158683797 
1.00250001250004074790133889386806610626172

Thanks,

Dick


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Re: Help with sympy, please

[Dick Moores]

At 05:24 PM 11/18/2007, Fredrik Johansson wrote:
>On Nov 19, 2007 2:03 AM, Dick Moores <[EMAIL PROTECTED]> wrote:
> > At 04:26 PM 11/18/2007, Fredrik Johansson wrote:
> > >On Nov 19, 2007 1:05 AM, Dick Moores <[EMAIL PROTECTED]> wrote:
> > >Hi Dick, I recognize you from python-list, where you had a question
> > >about mpmath.
> > >
> > >Your code still won't work if you convert the numbers to Floats
> > >because the Float type in sympy.numerics does not implement ** for
> > >fractional numbers. You could use the exp function in
> > >sympy.numerics.functions instead to compute e**x.
> >
> > Thanks, Fredrik, but I get the same error using either exp or power:
> > 
> > from __future__ import division
> > from sympy import *
> > from sympy import Rational as R
> > from sympy.numerics import *
> > from sympy.numerics.functions import power, exp
> >
> > prec = 50
> > Float.setdps(prec)
> > e = evalf(E)
> > n = 1
> > m = n + 1
> > k = 0
> > n = evalf(R(n,1))
> > m = evalf(R(m,1))
> > prod = evalf(R(1,1))
> > prec = 50
> > Float.setdps(prec)
> > e = evalf(E)
> > n = 1
> > k = 0
> > prod = evalf(R(1,1))
> > while k < 1000:
> >   k += 1
> >   n = evalf(R(n,1))
> >   term = (exp(1/n))/(exp(1/(n+1)))
> >   prod *= term
> >   n += 2
> > print prod, term
> > =
> > term = (exp(1/n))/(exp(1/(n+1)))
> > TypeError: unsupported operand type(s) for /: 'int' and 'Float'
> >
> > And also if I use sympy.numerics.functions.power in that line, as
> > term = power(e,(1/n))/power(e,(1/(n+1)))
> >
> > I get:
> >
> > term = power(e,(1/n))/power(e,(1/(n+1)))
> > TypeError: unsupported operand type(s) for /: 'int' and 'Float'
>
>Try not using "from __future__ import division".

Didn't help.


>Also,
>
>  n = evalf(R(n,1))
>
>won't work, because the arguments to Rational must be ints.

But both n and 1 are ints, aren't they?

Anyway, you've by now seen my new success with mpmath. I'll abandon 
syspy for the time being.

Dick

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Re: Help with sympy, please

[Dick Moores]

At 05:33 PM 11/18/2007, Fredrik Johansson wrote:
>On Nov 19, 2007 2:23 AM, Dick Moores <[EMAIL PROTECTED]> wrote:
> > OK, I tried mpmath again, and to my surprise, it went well!
> >
> > ===
> > #!/usr/bin/env python
> > #coding=utf-8
> > from mpmath import *
> > mpf.dps = 50
> > n = 1
> > k = 0
> > prod = mpf(1)
> > while k < 10:
> >  k += 1
> >  term = exp(1.0/n)/exp(1.0/(n+1))
> >  prod *= term
> >  n += 2
> > print prod, term
> > ==
> > Output:
> > 1.95187499635016028080844735182389158683797
> > 1.00250001250004074790133889386806610626172
>
>You're getting slightly wrong results, though, because 1.0/n and
>1.0/(n+1) just performs regular float division with ~16-digit
>precision when n is a Python int. You should convert either 1.0 or n
>to an mpf before dividing.

Ah, yes. That was my original mistake with using mpmath. How's this?:

=
#!/usr/bin/env python
#coding=utf-8
import psyco
psyco.full()
from mpmath import *
mpf.dps = 50
n = mpf(1)
k = 0
prod = mpf(1)
while k < 10:
 k += 1
 term = exp(1.0/n)/exp(1.0/(n+1))
 prod *= term
 n += 2
print prod, term
===
Output:
1.95187499635415917971337956346129920295869 
1.00250001250009375062500416669401059407666

Dick


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Trouble getting loop to break

[Dick Moores]

I'm writing a demo of the infinite series

x**0/0! + x**1/1! + x**2/2! + x**3/3! + ...   = e**x   (x is non-negative)

It works OK for many x, but for many the loop doesn't break. Is there 
a way to get it to break where I want it to, i.e., when the sum 
equals the limit as closely as the precision allows?

Here's what I have:

=== series_xToN_OverFactorialN.py ==
#!/usr/bin/env python
#coding=utf-8
# series_xToN_OverFactorialN.py  limit is e**x   from p.63 in The 
Pleasures of Pi,e
from mpmath import mpf, e, exp, factorial
import math
import time
precision = 100
mpf.dps = precision
n = mpf(0)
x = mpf(raw_input("Enter a non-negative int or float: "))
term = 1
sum = 0
limit = e**x
k = 0
while True:
 k += 1
 term = x**n/factorial(n)
 sum += term
 print " sum = %s k = %d" % (sum, k)
 print "exp(%s) = %s" % (x, exp(x))
 print "  e**%s = %s" % (x, e**x)
 print
 if sum >= limit:
 print "math.e**%s = %f" % (x, math.e**x)
 print "last term = %s" % term
 break
 time.sleep(0.2)
 n += 1

"""
Output for x == mpf(123.45):
sum = 
410822093109668964239148908443317876138879647013995774.2951431466270782257597573259486687336246984942
 
k = 427
exp(123.45) = 
410822093109668964239148908443317876138879647013995774.2951431466270782257597573259486687336246984942
   e**123.45 = 
410822093109668964239148908443317876138879647013995774.2951431466270782257597573259486687336246984942
"""


This is also on the web at <http://python.pastebin.com/f1a5b9e03>.

Examples of problem x's: 10, 20, 30, 40, 100, 101
Examples of OK x's: 0.2, 5, 10.1, 11, 33.3, 123.45

Thanks,

Dick Moores

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Re: Trouble getting loop to break

[Dick Moores]

At 12:45 AM 11/20/2007, Dennis Lee Bieber wrote:
>On Mon, 19 Nov 2007 23:41:02 -0800, Dick Moores <[EMAIL PROTECTED]>
>declaimed the following in comp.lang.python:
>
> > a way to get it to break where I want it to, i.e., when the sum
> > equals the limit as closely as the precision allows?
> >
>
> >  if sum >= limit:
>
> Well, since it ISN'T a case of testing for an absolute equivalence
>with floats...
>
> Perhaps putting a "print sum, limit" before that point would reveal
>what type of values you are encountering.

If you run the program you'll see exactly that, if I understand you 
correctly. <http://python.pastebin.com/f2f06fd76> shows the full 
output for a precision of 50 and x == 5.

Dick


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Re: Trouble getting loop to break

[Dick Moores]

At 03:53 AM 11/20/2007, Fredrik Johansson wrote:
>On Nov 20, 2007 8:41 AM, Dick Moores <[EMAIL PROTECTED]> wrote:
> > I'm writing a demo of the infinite series
> >
> > x**0/0! + x**1/1! + x**2/2! + x**3/3! + ...   = e**x   (x is non-negative)
> >
> > It works OK for many x, but for many the loop doesn't break. Is there
> > a way to get it to break where I want it to, i.e., when the sum
> > equals the limit as closely as the precision allows?
> >
> > Here's what I have:
> >
> > === series_xToN_OverFactorialN.py ==
> > #!/usr/bin/env python
> > #coding=utf-8
> > # series_xToN_OverFactorialN.py  limit is e**x   from p.63 in The
> > Pleasures of Pi,e
> > from mpmath import mpf, e, exp, factorial
> > import math
> > import time
> > precision = 100
> > mpf.dps = precision
> > n = mpf(0)
> > x = mpf(raw_input("Enter a non-negative int or float: "))
> > term = 1
> > sum = 0
> > limit = e**x
> > k = 0
> > while True:
> >  k += 1
> >  term = x**n/factorial(n)
> >  sum += term
> >  print " sum = %s k = %d" % (sum, k)
> >  print "exp(%s) = %s" % (x, exp(x))
> >  print "  e**%s = %s" % (x, e**x)
> >  print
> >  if sum >= limit:
> >  print "math.e**%s = %f" % (x, math.e**x)
> >  print "last term = %s" % term
> >  break
> >  time.sleep(0.2)
> >  n += 1
> >
> > """
> > Output for x == mpf(123.45):
> > sum =
> > 
> 410822093109668964239148908443317876138879647013995774.2951431466270782257597573259486687336246984942
> > k = 427
> > exp(123.45) =
> > 
> 410822093109668964239148908443317876138879647013995774.2951431466270782257597573259486687336246984942
> >e**123.45 =
> > 
> 410822093109668964239148908443317876138879647013995774.2951431466270782257597573259486687336246984942
> > """
> > 
> >
> > This is also on the web at <http://python.pastebin.com/f1a5b9e03>.
> >
> > Examples of problem x's: 10, 20, 30, 40, 100, 101
> > Examples of OK x's: 0.2, 5, 10.1, 11, 33.3, 123.45
> >
> > Thanks,
> >
> > Dick Moores
>
>Hi,
>
>Checking that sum >= e**x will generally not work, because e**x might
>have been rounded up while the sum might repeatedly be rounding down.
>If this happens, no matter how many terms you add, the sum will never
>reach the limit (one of the curses of finite-precision arithmetic).
>
>One solution is to use directed rounding. First compute the limit with
>downward rounding:
>
>mpf.round_down()
>limit = e**x
>mpf.round_default()
>
>Then compute every term in the sum with upward rounding:
>
>mpf.round_down()
>fac = factorial(n)
>mpf.round_up()
>term = x**n / fac
>sum += term
>
>(Note that the factorial should be rounded down to obtain upward
>rounding in the term, since you're taking its reciprocal.)
>
>This should guarantee that the sum eventually exceeds the limit.
>
>As a simpler, less rigorous alternative, instead of checking if sum >=
>limit, check (for example) whether
>
> abs(sum - limit) / limit <= mpf(10)**(-precision+3)
>
>i.e., if the sum is within 3 digits of the limit. This is the usual
>way to test for numerical equality of floating-point numbers.

I tried out both ways, and found that the second one best suited my 
purposes. Please see the 2 highlighted lines in 
<http://python.pastebin.com/fcc23b10>
Note that to break the loop I found that this does the job:

if abs(sum - limit) / limit <= mpf(10)**(-precision+1):#  I 
changed your +3 to +1
 break

Fredrik, thanks VERY much for your terrific instruction!

Dick


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Re: Trouble getting loop to break

[Dick Moores]

At 10:42 AM 11/20/2007, [EMAIL PROTECTED] wrote:
>Instead of comparing sum to the "known" value of e**x, why not test
>for convergence?  I.e., if sum == last_sum: break.  Seems like that
>would be more robust (you don't need to know the answer to computer
>the answer), since it seems like it should converge.

Yes! And believe it or not I did that before seeing your post. Works 
well. See 

And also with the amazing Chudnovsky algorithm for pi. See 


Thanks,

Dick


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Re: Trouble getting loop to break

[Dick Moores]

At 01:32 PM 11/20/2007, Fredrik Johansson wrote:
>On Nov 20, 2007 10:00 PM, Dick Moores <[EMAIL PROTECTED]> wrote:
> > And also with the amazing Chudnovsky algorithm for pi. See
> > <http://python.pastebin.com/f4410f3dc>
>
>Nice! I'd like to suggest two improvements for speed.
>
>First, the Chudnovsky algorithm uses lots of factorials, and it's
>rather inefficient to call mpmath's factorial function from scratch
>each time. You could instead write a custom factorial function that
>only uses multiplications and caches results, something like this:
>
>cached_factorials = [mpf(1)]
>
>def f(n):
> n = int(n)
> if n < len(cached_factorials):
> return cached_factorials[n]
> p = cached_factorials[-1]
> for i in range(len(cached_factorials), n+1):
> p *= i
> cached_factorials.append(p)
> return p
>
>(In some future version of mpmath, the factorial function might be
>optimized so that you won't have to do this.)
>
>Second, to avoid unnecessary work, factor out the fractional power of
>640320 that occurs in each term. That is, change the "denom =" line to
>
> denom = (f(3*k) * ((f(k))**3) * (640320**(3*k)))
>
>and then multiply it back in at the end:
>
> print 1/(12*sum/640320**(mpf(3)/2))
>
>With these changes, the time to compute 1,000 digits drops to only 
>0.05 seconds!
>
>Further improvements are possible.
>
>Fredrik

Fredrik,

I'm afraid I'm just too dumb to see how to use your first suggestion 
of cached_factorials. Where do I put it and def()? Could you show me, 
even on-line, what to do? <http://py77.python.pastebin.com/f48e4151c> 
You (or anyone) can submit an amendment to my code using the textbox.

I did make the denom change, and see that it does improve the speed a bit.

Thanks,

Dick




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Re: Trouble getting loop to break

[Dick Moores]

At 03:26 AM 11/25/2007, Fredrik Johansson wrote:
>On Nov 25, 2007 9:00 AM, Dick Moores <[EMAIL PROTECTED]> wrote:
> > Fredrik,
> >
> > I'm afraid I'm just too dumb to see how to use your first suggestion
> > of cached_factorials. Where do I put it and def()? Could you show me,
> > even on-line, what to do? <http://py77.python.pastebin.com/f48e4151c>
> > You (or anyone) can submit an amendment to my code using the textbox.
> >
> > I did make the denom change, and see that it does improve the speed a bit.
>
>I edited the pastebin code, see: http://py77.python.pastebin.com/m6b2b34b7
>
>Fredrik

Wow. your f() is ingenious, Frederik. Thanks very much.

Any more tricks up your sleeve? You did say a post or so ago, 
"Further improvements are possible."

Dick



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Re: Great Python books for the beginner

[Dick Moores]

At 11:03 PM 1/11/2008, Landon wrote:
>Hi, I'm a freshman in college and I'm going to be taking an intro to
>programming course next semester which mainly uses Python, so I
>thought it might be a good time to pick up Python beyond the scope of
>the class as well. The text book for this class is Python for the
>Absolute Beginner or something similar to that name.
>
>I was wondering if anyone had any opinions on what other titles I
>could look into since this one seems from a glance at reviews to be
>teaching mainly through game programming (a topic I'm not too
>interested in) or if this one is a quality book by itself.

Yes, it's a quality book, IMO.

I hope by now you've gotten over your dislike for online tutorials. 
Please take a look at these 3:
Hands-On Python <http://www.cs.luc.edu/~anh/python/hands-on/>
How to Think Like a (Python) Programmer 
<http://www.greenteapress.com/thinkpython/>
Alan Gauld's Learning to Program (heavy emphasis on Python) 
<http://www.freenetpages.co.uk/hp/alan.gauld>

Also, do take advantage of the VERY helpful Tutor mailing list. 
<http://mail.python.org/mailman/listinfo/tutor>.

Dick Moores

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Re: IDE Question

[Dick Moores]

Have you seen Kelie Feng's video introducing the terrific and free
IDE, Ulipad? <http://www.rcblue.com/u3/>
Get Ulipad 3.9 from <http://code.google.com/p/ulipad/downloads/list>
svn for the latest revision <http://ulipad.googlecode.com/svn/trunk/>
Mailing list for Ulipad: <http://groups-beta.google.com/group/ulipad>

Dick Moores 


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