Re: Functional schmunctional...
r0g wrote:
def ip2inet(a):
li = a.split('.')
assert len(li) == 4 or len(li) == 6
return reduce(add,[int(li[e])*(256**((len(li)-1)-e)) for e in
xrange(0,len(li))])
what a mess.
i don't use this extreme a functional style in python (it's not really how
the language is intended to be used), but i think you can do better than
that.
how about:
from itertools import count
def ip2inet(a):
blocks = a.split('.')
assert len(blocks) in (4, 6)
return sum(map(lambda (i, n): int(i) * 256**n,
zip(reversed(blocks), count(0
i haven't looked at the other function, but as a general comment it sounds
me like you are in such a hurry to point out fp is bad that you haven't
bothered to master it first.
andrew
--
http://mail.python.org/mailman/listinfo/python-list
Re: Functional schmunctional...
r0g aioe@technicalbloke.com writes:
def inet2ip(n):
p = (n/16777216)
q = ((n-(p*16777216))/65536)
r = ((n-((p*16777216)+(q*65536)))/256)
s = ((n-((p*16777216)+(q*65536)+(r*256
return str(p)+.+str(q)+.+str(r)+.+str(s)
from struct import pack
def inet2ip(n):
xs = pack('L',n)
return '.'.join(str(ord(x)) for x in xs)
--
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Replace unknow string varible in file.
Hey .python first time poster here. I'm pretty good with python so far, but I keep needed a function in my program but not knowing how to build it. =( Here's the problem: Imagine a html file full of 100's of these strings all mooshed together onto many lines; !--@@MARKER@@; id=ITEM--ITEMbr Where the word 'MARKER' is a constant, it stay the same in each string and the word 'ITEM' is a random combination of ascii characters of an unknown length. So for example a: !--@@MARKER@@; id=CATFISH--CATFISHbrh1Text text text/ h1!--@@MARKER@@; id=SPAM--SPAMbr and so on... What I need to do it replace each instance of the random letter with a constant and/or delete them. The file is a html file so the stuff inside of !-- -- is ok to keep and I need that data to identify where the strings are in the file (it's full of other stuff too). I'm tired making a bruteforcer but with unknown length and 26 letters of the alphabet I gave up because it would take too long (it was something like; read file; if '@@MARKER@@; id='+str(gen_string)+'-- +sr(gen_string)+'br' in file then replace with '', but I'm paraphrasing code and it's not the best solution anyway). Just as a comparison in the Windows OS this seems easy to do when managing files, say for the file a-blah-b-blah.tmp where blah is an unknown you can use: del a-*-b-*.tmp to get rid of that file. But for python and a string in text file I don't have a clue. @_@ could someone please help me? -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Module: nift
J wrote: Thanks for your answers, especially Chris Rebert and Paul McGuire's. I have a question: How far does Python go in the Game Development field? (Using Python only, no extensions) Hey J, Python's all about the libraries (extensions), you won't be able to do much without them but that's no big whoop. AFAIK most python libs are released under LGPL or BSD style licenses so there's pretty much no restriction on what you can use them for. A lot of games are written in C for performance reasons but most python gaming libs are just wrappers round C gaming libs and share the same names and methods so your knowledge should travel with you. As for which libs to use... There's PyGame which is a a good mature library for 2D stuff. Pyglet seem to be the most popular OpenGL lib for 3D stuff. You might also want to look at the Blender Game Engine and the free game Yo Frankie, they use C for the heavy lifting and Python for scripting levels and stuff, it might be a good way to test the waters. Regards, Roger Heathcote. -- http://mail.python.org/mailman/listinfo/python-list
zlib interface semi-broken
Hello all, The zlib interface does not indicate when you've hit the end of a compressed stream. The underlying zlib functionality provides for this. With python's zlib, you have to read past the compressed data and into the uncompressed, which gets stored in Decompress.unused_data. As a result, if you've got a network protocol which mixes compressed and non-compressed output, you may find a compressed block ending with no uncompressed data following until you send another command -- which a synchronous (non-pipelined) client will not send, because it is waiting for the [compressed] data from the previous command to be finished. As a result, you get a protocol deadlock. A simple way to fix this would be to add a finished attribute to the Decompress object. However, perhaps this would be a good time to discuss how this library works; it is somewhat awkward and perhaps there are other changes which would make it cleaner. What does the python community think? -- Crypto ergo sum. http://www.subspacefield.org/~travis/ Do unto other faiths as you would have them do unto yours. If you are a spammer, please email j...@subspacefield.org to get blacklisted. -- http://mail.python.org/mailman/listinfo/python-list
optparse versus getopt
does anyone have any arguments against optparse vs getopt -- http://mail.python.org/mailman/listinfo/python-list
pySerial help please!
Hello all, I am very new to Python and I am using it because I needed an easy language to control a piece of equipment that connects to my computer via a serial cable. I am running Python 2.6 with pySerial 2.4 under Windows. I can get Python to create a serial port on COM1, but when I try to write to the device, nothing happens. Here is an example: import serial ser = serial.Serial(0) ser.write(otpm 2 16 0) ser.close() If I connect to the device in Hyperterminal the device will behave as expected when I give it the command 'otpm 2 16 0' but not in Python. I have confirmed Python is actually controlling the port because Hyperterminal will not open the port while Python has it open, although I have not been able to try a loopback connector as of yet. Any suggestions out there? Thanks in advance! Cheers, Bryce -- http://mail.python.org/mailman/listinfo/python-list
Re: optparse versus getopt
On 2009-02-10 15:06, Matthew Sacks wrote: does anyone have any arguments against optparse vs getopt As the getopt docs say: A more convenient, flexible, and powerful alternative is the optparse module. I have found all three statements to be true. But I've found argparse to be even better. The main reason is that argparse will help you parse, verify and generate help text for positional arguments in addition to --options. http://argparse.python-hosting.com/ http://argparse.python-hosting.com/wiki/ArgparseVsOptparse -- Robert Kern I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth. -- Umberto Eco -- http://mail.python.org/mailman/listinfo/python-list
Re: Functional schmunctional...
For expressiveness, try something like:
def ip2in(dotted_ip_addr):
result = 0
assert dotted_ip_addr.count('.') in (3, 7)
for chunk in dotted_ip_addr.split('.'):
result = (result 8) + int(chunk)
return result
def inet2ip(ip_number):
assert 0 ip_number 1 48
bytes = []
while ip_number:
bytes.append(ip_number 255)
ip_number = 8
assert len(bytes) in (4, 6)
return '.'.join(str(n) for n in reversed(bytes))
--Scott David Daniels
scott.dani...@acm.org
--
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Re: Replace unknow string varible in file.
2009/2/10 namire nam...@gmail.com: Hey .python first time poster here. I'm pretty good with python so far, but I keep needed a function in my program but not knowing how to build it. =( Here's the problem: Imagine a html file full of 100's of these strings all mooshed together onto many lines; !--@@MARKER@@; id=ITEM--ITEMbr Where the word 'MARKER' is a constant, it stay the same in each string and the word 'ITEM' is a random combination of ascii characters of an unknown length. So for example a: !--@@MARKER@@; id=CATFISH--CATFISHbrh1Text text text/ h1!--@@MARKER@@; id=SPAM--SPAMbr and so on... What I need to do it replace each instance of the random letter with a constant and/or delete them. ... Just as a comparison in the Windows OS this seems easy to do when managing files, say for the file a-blah-b-blah.tmp where blah is an unknown you can use: del a-*-b-*.tmp to get rid of that file. But for python and a string in text file I don't have a clue. @_@ could someone please help me? -- http://mail.python.org/mailman/listinfo/python-list Hi, It is not quite clear to me, what should be achieved with the given file, but an example with wildcard characters in windows implies, that the regular expressions can be of some use here (given the file is as regular as the samples, especially without nesting the comments etc.) the segments in examples can be matched eg. with the expression: !--@@MARKER@@; id=([^]+)--\1br the ITEM, CATFISH, SPAM ... elements are captured in the parethesised group and can be used foe matching or replacing. check the re module in the python library: http://docs.python.org/library/re.html hth vbr -- http://mail.python.org/mailman/listinfo/python-list
Re: bool evaluations of generators vs lists
On Tue, 2009-02-10 at 12:50 -0800, Josh Dukes wrote: The thing I don't understand is why a generator that has no iterable values is different from an empty list. Why shouldn't bool == has_value?? Technically a list, a tuple, and a string are also objects but if they lack values they're evaluated as False. It seems to me that a generator is an object that intends to replace lists where lazy evaluation would be more efficent. Here is one place where that's definitely true. Well, I did not implement generators in python, but my guess would be that lists and tuples can be checked with len() to see if it is non-empty. Generators don't have length. You would at least need to call .next() which changes the generator so every time you'd want to evaluate the boolean of the generator you'd potentially lose the next item. Generators are meant to replace lists where you don't want/can't put the entire list in memory or for which there is no (known) end to the list. You don't know the next value a generator will return (if any) until you evaluate it. Don't think of generators as containers like lists, tuples and strings are. Generators don't contain values. Generators are objects that return the next value. It has no idea how many values it contains (it's not a container). It only knows the .next() value when it's called. It forgets the value once it's returned. And it has no idea how far it is in the iteration until it's finished (StopIteration). The main reason I'm interested in this is that it improves performance immensely over boolean evaluation of large lists (as the attached code shows). It seems to me if I could use find a good use for it in my experimentation that someone else might also want to do the same thing in real-world code. I don't understand what you mean by this. But if you really want to know if a generator is non-empty: def non_empty(virgin_generator): try: virgin_generator.next() # note you just lost the first value return True except StopIteration: return False The only way to get around this is to put all the values of a generator inside a container (e.g. a list): l = list(generator_object) but in doing so you've (obviously) lost the advantages of the generator. Is there another list I should be asking these questions on? I don't know. Sorry I wasn't able to help you. -a -- http://mail.python.org/mailman/listinfo/python-list
Re: zlib interface semi-broken
Travis wrote: The zlib interface does not indicate when you've hit the end of a compressed stream The underlying zlib functionality provides for this. With python's zlib, you have to read past the compressed data and into the uncompressed, which gets stored in Decompress.unused_data. ... [good explanation of why this is problematic] ... A simple way to fix this would be to add a finished attribute to the Decompress object. Perhaps you could submit a patch with such a change? However, perhaps this would be a good time to discuss how this library works; it is somewhat awkward and perhaps there are other changes which would make it cleaner. Well, it might be improvable, I haven't really looked. I personally would like it and bz2 to get closer to each other in interface, rather than to spread out. SO if you are really opening up a can of worms, I vote for two cans. --Scott David Daniels scott.dani...@acm.org -- http://mail.python.org/mailman/listinfo/python-list
Re: optparse versus getopt
Matthew Sacks wrote: does anyone have any arguments against optparse vs getopt I've found that the optparse module beats getopt on *every* aspect except in the event that you have experience with the C getopt libraries *and* just want something that behaves like those libraries. Optparse is easy to learn, easy to read, and part of the Python stdlib. -tkc -- http://mail.python.org/mailman/listinfo/python-list
Re: Logging in Python
Thanks for your suggestions. I've also figured that I can test if logging.RootLogger.manager.loggerDict has any items in it. Or if it has a logger for the module that I wish to start. I like basicLogger idea though as it seems like the cleanest implementation. On Feb 10, 3:21 pm, Vinay Sajip vinay_sa...@yahoo.co.uk wrote: On Feb 10, 5:50 pm, aha aquil.abdul...@gmail.com wrote: Hello All, I have an application whereloggingmay need to be configured in multiple places. I've used the PythonLoggingFramework for sometime, but I'm still not sure how to test iflogginghas configured. For example, I have modules A, B, and C. Below is some pseudo code... moduleA class A(object): def __init__(self): ... startLogging(config): # Configurelogging # global logger ... moduleB import moduleA from myconfig import MyConfig class B(object): def __init__(self): # self.config = MyConfig() # iflogginghas started [HOW DO YOU DO THIS?] # self.logger =logging.getLogger(moduleB) # else # self.logger = moduleA.startLogging(self.config) # moduleA.startLogging ... Where I need help is determining if a logger has already been configured. Any advice? Aquil It depends upon how complicated your logging requirements are. For example, each module can have the following code in it: import logging logging.basicConfig(level=logging.DEBUG, filename=/tmp/myapp.log, filemode=w) # An example logger = logging.getLogger(__name__) ... your code, involving logger.debug(...) statements basicConfig() attaches a FileLogger to the root logger, so all logging output would be routed to the file /tmp/myapp.log in the example. However, basicConfig() does nothing if the root logger already has handlers, so calling it in each module shouldn't cause problems. It's also nice to use the module name (__name__) as the logger name. Another pattern is to configure logging in your main module, if there is one, and then the other modules just assume logging is configured and log away. If there isn't a main module, have all the modules import a common module which, when imported, configures logging how you want it. Under normal circumstances, the import code will only run once, so your logging only gets configured the first time the module gets imported by any of the others. Regards, Vinay Sajip -- http://mail.python.org/mailman/listinfo/python-list
Re: optparse versus getopt
it seems as if optparse isn't in my standard library. is there a way to add a lib like ruby gems? On Tue, Feb 10, 2009 at 1:38 PM, Tim Chase python.l...@tim.thechases.com wrote: Matthew Sacks wrote: does anyone have any arguments against optparse vs getopt I've found that the optparse module beats getopt on *every* aspect except in the event that you have experience with the C getopt libraries *and* just want something that behaves like those libraries. Optparse is easy to learn, easy to read, and part of the Python stdlib. -tkc -- http://mail.python.org/mailman/listinfo/python-list
Cannot get python to read a CAP file link in an ATOM feed
Hi List, I'm trying to get python to parse a CAP file in an ATOM feed from the National Weather Service. Here's one states ATOM feed. http://www.weather.gov/alerts-beta/ky.php?x=0. If you view the source of this file, there is a reference to another web feed. For instance, href=http://www.weather.gov/alerts-beta/wwacapget.php?x=KY20090210210200ILNNPWILNHighWindWarning2009021210KY; (note, this latter file changes hourly). I can retrieve and parse the first file but cannot get the second file read or parsed as an xml. I am able to read it into memory using urlopen. Can python read and parse as an xml or do I need to read it into memory. If it is in memory, is there a similar parsing function. Thanks Brian Kaplan -- http://mail.python.org/mailman/listinfo/python-list
Re: optparse versus getopt
On 2009-02-10 15:42, Matthew Sacks wrote: it seems as if optparse isn't in my standard library. How did you install your Python? It has been part of the standard library for a very long time. is there a way to add a lib like ruby gems? http://docs.python.org/install/index.html But optparse (named Optik when it was a separate package) has not been distributed separately from Python for a long time. -- Robert Kern I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth. -- Umberto Eco -- http://mail.python.org/mailman/listinfo/python-list
Re: Using TK and the canvas.
On Feb 11, 5:51 am, r rt8...@gmail.com wrote: On Feb 10, 1:27 pm, Kalibr space.captain.f...@gmail.com wrote: [snip] You should really check out wxPython, there is support for just this type of thing. of course you could do this with Tkinter, but just thinking about it makes my head hurt :). Alright, I shall investigate. Thank you. -- http://mail.python.org/mailman/listinfo/python-list
Re: GAE read binary file into db.BlobProperty()
was not able to use open to open a binary file so what I did was use urlfetch to fetch the image for me and read the content into BlobProperty() Not sure why it took me so long to figure this out. Hope it helps someone. thx def post(self,key): k=db.get(key) img=images.Image(urlfetch.Fetch(http://www.example.com/ +k.image).content) img.rotate(90) jpg_data= img.execute_transforms(images.JPEG) k.image_blob=jpg_data k.put() -Alex Goretoy http://www.goretoy.com On Mon, Feb 9, 2009 at 11:07 AM, alex goretoy aleksandr.gore...@gmail.comwrote: How to read Binary file into GAE(Google App Engine) db.BlobProperty() datastore? -Alex Goretoy http://www.goretoy.com -- http://mail.python.org/mailman/listinfo/python-list
Re: zlib interface semi-broken
Travis travis+ml-pyt...@subspacefield.org writes: However, perhaps this would be a good time to discuss how this library works; it is somewhat awkward and perhaps there are other changes which would make it cleaner. What does the python community think? It is missing some other features too, like the ability to preload a dictionary. I'd support extending the interface. -- http://mail.python.org/mailman/listinfo/python-list
Re: Functional schmunctional...
Here a small benchmark:
def ip2inet01(a): # can't be used with 6
li = a.split('.')
assert len(li) == 4
a = int(li[0])*16777216
b = int(li[1])*65536
c = int(li[2])*256
d = int(li[3])
return a+b+c+d
from itertools import count
def ip2inet02(a):
blocks = a.split('.')
assert len(blocks) in (4, 6)
return sum(map(lambda (i, n): int(i) * 256**n, zip(reversed
(blocks), count(0
def ip2inet03(iptxt):
bytes = map(int, iptxt.strip().split(.))[::-1]
assert len(bytes) in (4, 6)
return sum(by * 256**po for po, by in enumerate(bytes))
def ip2inet04(iptxt):
bytes = map(int, reversed(iptxt.strip().split(.)))
assert len(bytes) in (4, 6)
powers256 = [1, 256, 65536, 16777216, 4294967296, 1099511627776]
return sum(by * powers256[po] for po, by in enumerate(bytes))
def ip2inet05(iptxt):
bytes = (int(by) for by in reversed(iptxt.strip().split(.)))
parts = [by * ip2inet05.powers256[po] for po, by in enumerate
(bytes)]
assert len(parts) in (4, 6)
return sum(parts)
ip2inet05.powers256 = [1, 256, 65536, 16777216, 4294967296,
1099511627776]
def ip2inet06(a):
li = a.split('.')
n = len(li)
assert n == 4 or n == 6
if n == 4:
return (int(li[0]) * 16777216 +
int(li[1]) * 65536 +
int(li[2]) * 256 +
int(li[3]))
else:
return (int(li[0]) * 1099511627776 +
int(li[1]) * 4294967296 +
int(li[2]) * 16777216 +
int(li[3]) * 65536 +
int(li[4]) * 256 +
int(li[5]))
def ip2inet07(iptxt):
bytes = map(int, iptxt.strip().split(.))[::-1]
assert len(bytes) in (4, 6)
return sum(by * ip2inet07.pows[po] for po, by in enumerate(bytes))
ip2inet07.pows = [1, 256, 65536, 16777216, 4294967296, 1099511627776]
from struct import pack
def ip2inet08(n): # error
xs = pack('L', n)
return '.'.join(str(ord(x)) for x in xs)
def ip2inet09(iptxt): # short and readable
bytes = map(int, iptxt.strip().split(.))[::-1]
assert len(bytes) in (4, 6)
return sum(by (8*po) for po, by in enumerate(bytes))
def ip2inet10(iptxt):
count = 0
result = 0
for byte in iptxt.strip().split(.):
result = 8
result += int(byte)
count += 1
assert count in (4, 6)
return result
def ip2inet11(iptxt):
bytes = iptxt.strip().split(.)
assert len(bytes) in (4, 6)
result = 0
for byte in bytes:
result = 8
result += int(byte)
return result
def ip2inet12(iptxt):
bytes = iptxt.strip().split(.)
assert len(bytes) in (4, 6)
result = 0
for byte in bytes:
result = (result 8) + int(byte)
return result
def ip2inet13(a): # fastest and readable
li = a.split('.')
n = len(li)
assert n == 4 or n == 6
if n == 4:
return ((int(li[0]) 24) +
(int(li[1]) 16) +
(int(li[2]) 8) +
int(li[3]))
else:
return ((int(li[0]) 40) +
(int(li[1]) 32) +
(int(li[2]) 24) +
(int(li[3]) 16) +
(int(li[4]) 8) +
int(li[5]))
def main():
from timeit import default_timer as clock
ip4 = 155.16.187.87
ip6 = 7.155.16.187.87.255
algos = [ip2inet02, ip2inet03, ip2inet04, ip2inet05, ip2inet06,
ip2inet07, ip2inet09, ip2inet10, ip2inet11, ip2inet12,
ip2inet13]
for algo in algos:
assert algo(ip4) == 2601565015 and algo(ip6) == 8362582038527
t0 = clock()
for i in xrange(1):
algo(ip4)
algo(ip6)
print algo.__name__, round(clock() - t0, 2), s
import psyco; psyco.full()
print With Psyco:
for algo in algos:
t0 = clock()
for i in xrange(1):
algo(ip4)
algo(ip6)
print algo.__name__, round(clock() - t0, 2), s
main()
ip2inet02 2.68 s
ip2inet03 1.79 s
ip2inet04 1.72 s
ip2inet05 1.88 s
ip2inet06 0.98 s
ip2inet07 1.57 s
ip2inet09 1.5 s
ip2inet10 1.07 s
ip2inet11 1.07 s
ip2inet12 1.03 s
ip2inet13 0.95 s
With Psyco (indipendent run! Not normally successive):
ip2inet02 2.66 s
ip2inet03 1.66 s
ip2inet04 1.97 s
ip2inet05 1.66 s
ip2inet06 0.57 s
ip2inet07 1.5 s
ip2inet09 1.54 s
ip2inet10 0.53 s
ip2inet11 0.76 s
ip2inet12 0.52 s
ip2inet13 0.8 s
So if you need speed you the version #13 is better, if you want short
and readable code (but not too much slow) you can use #9, and if you
want code easy to understand by every one and easy to translate to
other languages then you can use #12.
Bye,
bearophile
--
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Re: bool evaluations of generators vs lists
On Tue, 10 Feb 2009 12:50:02 -0800, Josh Dukes wrote: The thing I don't understand is why a generator that has no iterable values is different from an empty list. How do you know it has no iterable values until you call next() on it and get StopIteration? By the way, your has_values function is just a slower version of the built-in any(). -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Re: can multi-core improve single funciton?
On Tue, 10 Feb 2009 12:43:20 +, Lie Ryan wrote: Of course multi-core processor can improve single function using multiprocessing, as long as the function is parallelizable. The Fibonacci function is not a parallelizable function though. As I understand it, there's very little benefit to multi-cores in Python due to the GIL. -- Steven. -- http://mail.python.org/mailman/listinfo/python-list
Re: generator object or 'send' method?
Aaron Brady wrote: I guess a generator that counts, but skips K numbers, where K can be varied. For instance, you initialize it with N, the starting number, and K, the jump size. Then, you can change either one later on. This specification is incomplete as to the timing of when changes to N take effect and when variable K is applied. This gets two birds with one stone, but is it possible? If you write an iterator class instead of trying to stretch the abbreviated form beyond its intention, and the specification is coherent, it should be trivial. -- http://mail.python.org/mailman/listinfo/python-list
Re: Replace unknow string varible in file.
namire wrote: Just as a comparison in the Windows OS this seems easy to do when managing files, say for the file a-blah-b-blah.tmp where blah is an unknown you can use: del a-*-b-*.tmp to get rid of that file. But for python and a string in text file I don't have a clue. @_@ could someone please help me? Hi Namire, The equivalent thing in programming languages is Regular Expressions, also known as regex. It's like a small pattern matching sub-language. There quite a lot more to it than the odd * so it might take a bit of googling around and study to really understand it but the principle is the same. In python you need to import the 're' module. Have a look at this, the replace method is called 'sub'... http://www.amk.ca/python/howto/regex/regex.html Take your time with it though, it can be confusing until you get used to it and when you're building an expression don't try and do it all at once, start small and build it up a little at a time. Roger Heathcote. -- http://mail.python.org/mailman/listinfo/python-list
Re: can multi-core improve single funciton?
On Tue, 10 Feb 2009 22:41:25 +1000, Gerhard Weis wrote: btw. the timeings are not that different for the naive recursion in OP's version and yours. fib(500) on my machine: OP's: 0.00116 (far away from millions of years) This here: 0.000583 I don't believe those timings are credible. On my machine, it took a minute to calculate fib(38), and while my machine isn't exactly the fastest box possible, nor is it especially slow. I don't wish to imply that you are deliberately lying, but your result of 0.00116 seconds for the naive version of fib(500) is so unrealistic in my experience that I believe you must be confused. Perhaps you've timed a less naive fib() but thought it was the naive version. Unless somebody can point out an error in my analysis, I'm sticking to my earlier claim that the naive version of fib(500) requires an unbelievably huge number of function calls: significantly more than the value of fib (500) itself. See my earlier post in this thread for details. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Re: Scanning a file character by character
On Tue, 10 Feb 2009 12:06:06 +, Duncan Booth wrote:
Steven D'Aprano ste...@remove.this.cybersource.com.au wrote:
On Mon, 09 Feb 2009 19:10:28 -0800, Spacebar265 wrote:
How would I do separate lines into words without scanning one
character at a time?
Scan a line at a time, then split each line into words.
for line in open('myfile.txt'):
words = line.split()
should work for a particularly simple-minded idea of words.
Or for a slightly less simple minded splitting you could try re.split:
re.split((\w+), The quick brown fox jumps, and falls over.)[1::2]
['The', 'quick', 'brown', 'fox', 'jumps', 'and', 'falls', 'over']
Perhaps I'm missing something, but the above regex does the exact same
thing as line.split() except it is significantly slower and harder to
read.
Neither deal with quoted text, apostrophes, hyphens, punctuation or any
other details of real-world text. That's what I mean by simple-minded.
--
Steven
--
http://mail.python.org/mailman/listinfo/python-list
Re: bool evaluations of generators vs lists
On Tue, Feb 10, 2009 at 1:57 PM, Steven D'Aprano ste...@remove.this.cybersource.com.au wrote: On Tue, 10 Feb 2009 12:50:02 -0800, Josh Dukes wrote: The thing I don't understand is why a generator that has no iterable values is different from an empty list. How do you know it has no iterable values until you call next() on it and get StopIteration? By the way, your has_values function is just a slower version of the built-in any(). nitpick Not quite: if the generator produces one or more elements but those elements happen to be boolean false according to Python, then any() will be false but has_values() will be true. The functions serve different purposes (produces at least 1 value vs. has at least one true value). Cheers, Chris -- Follow the path of the Iguana... http://rebertia.com -- http://mail.python.org/mailman/listinfo/python-list
Re: bool evaluations of generators vs lists
ahhh any! ok, yeah, I guess that's what I was looking for. Thanks. On 10 Feb 2009 21:57:56 GMT Steven D'Aprano ste...@remove.this.cybersource.com.au wrote: On Tue, 10 Feb 2009 12:50:02 -0800, Josh Dukes wrote: The thing I don't understand is why a generator that has no iterable values is different from an empty list. How do you know it has no iterable values until you call next() on it and get StopIteration? By the way, your has_values function is just a slower version of the built-in any(). -- Josh Dukes MicroVu IT Department -- http://mail.python.org/mailman/listinfo/python-list
Re: Logging in Python
On Feb 10, 9:38 pm, aha aquil.abdul...@gmail.com wrote: Thanks for your suggestions. I've also figured that I can test iflogging.RootLogger.manager.loggerDict has any items in it. Or if it has a logger for the module that I wish to start. I like basicLogger idea though as it seems like the cleanest implementation. It's best not to dig into the implementation details, as these might change across versions of Python. Any of the suggestions that Robert and I made should be able to solve your problem in the right way. Best regards, Vinay Sajip -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Launcher.app on OS X
So how does this effect the install instructions found on the link: http://wiki.python.org/moin/MacPython/Leopard do you trash that when you do an install on OS X? I am so hesitant to delete anything that resides in /System -- http://mail.python.org/mailman/listinfo/python-list
Re: bool evaluations of generators vs lists
Josh Dukes wrote: I was actually aware of that (thank you, though, for trying to help). What I was not clear on was if the boolean evaluation is a method of an object that can be modified via operatior overloading (in the same way + is actually .__add__()) or not. Clearly __nonzero__ is the operator I was curious about. Thanks for that info. .__bool__ in 3.0. The thing I don't understand is why a generator that has no iterable values is different from an empty list. Why shouldn't bool == has_value?? Technically a list, a tuple, and a string are also objects but if they lack values they're evaluated as False. It seems to me that a generator is an object that intends to replace lists where lazy evaluation would be more efficent. Here is one place where that's definitely true. Generator functions are abbreviated iterator classes. If you want iterators with more functionality, write an iterator class. In particular, you can add a .__bool__ method for empty or not or even a .__len__ method if you can accurately calculate the number of items remaining. The main reason I'm interested in this is that it improves performance immensely over boolean evaluation of large lists (as the attached code shows). It seems to me if I could use find a good use for it in my experimentation that someone else might also want to do the same thing in real-world code. Terry Jan Reedy -- http://mail.python.org/mailman/listinfo/python-list
Re: can multi-core improve single funciton?
On Tue, 10 Feb 2009 02:05:35 -0800, Niklas Norrthon wrote:
According to the common definition of fibonacci numbers fib(0) = 0, fib
(1) = 1 and fib(n) = fib(n-1) + fib(n-2) for n 1. So the number above
is fib(501).
So it is. Oops, off by one error!
Or, if you prefer, it's the right algorithm for a Lucas sequence with
first two values 1 and 1 instead of 0 and 1. :)
timeit.Timer('fib(500)', 'from __main__ import fib').timeit(1)
0.00083398818969726562
And now for my version (which admitedly isn't really mine, and returns
slightly incorrect fib(n) for large values of n, due to the limited
floating point precision).
The floating point version is nice, but it starts giving incorrect
answers relatively early, from n=71. But if you don't need accurate
results (a relative error of 3e-15 for n=71), it is very fast.
--
Steven
--
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RE: Python binaries with VC++ 8.0?
bearophileh...@lycos.com wrote: Paul Rubin: Gideon Smeding of the University of Utrecht has written a masters' thesis titled An executable operational semantics for Python. A significant part of Computer Science is a waste of time and money. The same can be said for any research. Can you predict ahead of time which research will be useful, and which won't? If so (and you can prove it) why aren't you making unbelievable amounts of money? Tim Delaney -- http://mail.python.org/mailman/listinfo/python-list
Re: Working with propositional formulae in Python
nnp wrote: Hey, I'm currently working with propositional boolean formulae of the type 'A (b - c)' (for example). I was wondering if anybody knows of a Python library to create parse trees and convert such formulae to conjunctive, disjunctive and Tseitin normal forms? You would probably do better with Google. Python conjunctive normal form gave some potentially interesting hits. -- http://mail.python.org/mailman/listinfo/python-list
Re: zlib interface semi-broken
Paul Rubin wrote: Travis travis+ml-pyt...@subspacefield.org writes: However, perhaps this would be a good time to discuss how [zlib] works... It is missing some other features too, like the ability to preload a dictionary. I'd support extending the interface. The trick to defining a preload interface is avoiding creating a brittle interface -- the saved preload should be usable across machines and versions. I suspect that is why such an interface never came up (If you can clone states, then you can say: compress this, then use the resultant state to compress/decompress others. Suddenly there is no nasty problem guessing what to parameterize and what to fix in stone. --Scott David Daniels scott.dani...@acm.org -- http://mail.python.org/mailman/listinfo/python-list
Re: can multi-core improve single funciton?
On 2009-02-11 08:01:29 +1000, Steven D'Aprano ste...@remove.this.cybersource.com.au said: On Tue, 10 Feb 2009 22:41:25 +1000, Gerhard Weis wrote: btw. the timeings are not that different for the naive recursion in OP's version and yours. fib(500) on my machine: OP's: 0.00116 (far away from millions of years) This here: 0.000583 I don't believe those timings are credible. On my machine, it took a minute to calculate fib(38), and while my machine isn't exactly the fastest box possible, nor is it especially slow. I don't wish to imply that you are deliberately lying, but your result of 0.00116 seconds for the naive version of fib(500) is so unrealistic in my experience that I believe you must be confused. Perhaps you've timed a less naive fib() but thought it was the naive version. Unless somebody can point out an error in my analysis, I'm sticking to my earlier claim that the naive version of fib(500) requires an unbelievably huge number of function calls: significantly more than the value of fib (500) itself. See my earlier post in this thread for details. I am sorry for the wrong timing, I mixed up the function names. The naive version used partly your version and partly the naive recursion. So less naive is a good description :) after fixing it: naive fib(38): ~40seconds -- http://mail.python.org/mailman/listinfo/python-list
Re: pySerial help please!
bmasch...@gmail.com wrote: Hello all, I am very new to Python and I am using it because I needed an easy language to control a piece of equipment that connects to my computer via a serial cable. I am running Python 2.6 with pySerial 2.4 under Windows. I can get Python to create a serial port on COM1, but when I try to write to the device, nothing happens. Here is an example: import serial ser = serial.Serial(0) ser.write(otpm 2 16 0) ser.close() If I connect to the device in Hyperterminal the device will behave as expected when I give it the command 'otpm 2 16 0' but not in Python. I have confirmed Python is actually controlling the port because Hyperterminal will not open the port while Python has it open, although I have not been able to try a loopback connector as of yet. Any suggestions out there? Thanks in advance! Have you checked that the baud rate, parity, etc, are the same as in Hyperterminal? -- http://mail.python.org/mailman/listinfo/python-list
Re: pySerial help please!
bmasch...@gmail.com schrieb: Hello all, I am very new to Python and I am using it because I needed an easy language to control a piece of equipment that connects to my computer via a serial cable. I am running Python 2.6 with pySerial 2.4 under Windows. I can get Python to create a serial port on COM1, but when I try to write to the device, nothing happens. Here is an example: import serial ser = serial.Serial(0) ser.write(otpm 2 16 0) ser.close() If I connect to the device in Hyperterminal the device will behave as expected when I give it the command 'otpm 2 16 0' but not in Python. I have confirmed Python is actually controlling the port because Hyperterminal will not open the port while Python has it open, although I have not been able to try a loopback connector as of yet. Any suggestions out there? Thanks in advance! You need to give a newline, you press return on the terminal as well, don't you? Diez -- http://mail.python.org/mailman/listinfo/python-list
Re: Scanning a file character by character
Or for a slightly less simple minded splitting you could try re.split: re.split((\w+), The quick brown fox jumps, and falls over.)[1::2] ['The', 'quick', 'brown', 'fox', 'jumps', 'and', 'falls', 'over'] Perhaps I'm missing something, but the above regex does the exact same thing as line.split() except it is significantly slower and harder to read. Neither deal with quoted text, apostrophes, hyphens, punctuation or any other details of real-world text. That's what I mean by simple-minded. s = The quick brown fox jumps, and falls over. import re re.split(r(\w+), s)[1::2] ['The', 'quick', 'brown', 'fox', 'jumps', 'and', 'falls', 'over'] s.split() ['The', 'quick', 'brown', 'fox', 'jumps,', 'and', 'falls', 'over.'] Note the difference in jumps vs. jumps, (extra comma in the string.split() version) and likewise the period after over. Thus not quite the exact same thing as line.split(). I think an easier-to-read variant would be re.findall(r\w+, s) ['The', 'quick', 'brown', 'fox', 'jumps', 'and', 'falls', 'over'] which just finds words. One could also just limit it to letters with re.findall([a-zA-Z], s) as \w is a little more encompassing (letters and underscores) if that's a problem. -tkc -- http://mail.python.org/mailman/listinfo/python-list
Re: Scanning a file character by character
On Tue, 10 Feb 2009 22:02:57 -, Steven D'Aprano
ste...@remove.this.cybersource.com.au wrote:
On Tue, 10 Feb 2009 12:06:06 +, Duncan Booth wrote:
Steven D'Aprano ste...@remove.this.cybersource.com.au wrote:
On Mon, 09 Feb 2009 19:10:28 -0800, Spacebar265 wrote:
How would I do separate lines into words without scanning one
character at a time?
Scan a line at a time, then split each line into words.
for line in open('myfile.txt'):
words = line.split()
should work for a particularly simple-minded idea of words.
Or for a slightly less simple minded splitting you could try re.split:
re.split((\w+), The quick brown fox jumps, and falls over.)[1::2]
['The', 'quick', 'brown', 'fox', 'jumps', 'and', 'falls', 'over']
Perhaps I'm missing something, but the above regex does the exact same
thing as line.split() except it is significantly slower and harder to
read.
Neither deal with quoted text, apostrophes, hyphens, punctuation or any
other details of real-world text. That's what I mean by simple-minded.
You're missing something :-) Specifically, the punctuation gets swept
up with the whitespace, and the extended slice skips it. Apostrophes
(and possibly hyphenation) are still a bit moot, though.
--
Rhodri James *-* Wildebeeste Herder to the Masses
--
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Re: Functional schmunctional...
r0g wrote: def inet2ip(n): p = (n/16777216) q = ((n-(p*16777216))/65536) r = ((n-((p*16777216)+(q*65536)))/256) s = ((n-((p*16777216)+(q*65536)+(r*256 return str(p)+.+str(q)+.+str(r)+.+str(s) Beyond what other wrote: To future-proof code, use // instead of / for integer division. To get both quotient and remainder, use divmod(num,den) For future reading (and generalization) documenting magic constants helps. In 3.0: def inet2ip(n): p = (n//16777216) q = ((n-(p*16777216))//65536) r = ((n-((p*16777216)+(q*65536)))//256) s = ((n-((p*16777216)+(q*65536)+(r*256 return str(p)+.+str(q)+.+str(r)+.+str(s) def inet2ip2(n): p,n=divmod(n,16777216) # 124 q,n=divmod(n,65536) # 116 r,s=divmod(n,256) # 18 return str(p)+.+str(q)+.+str(r)+.+str(s) print(inet2ip(10), inet2ip2(10)) 59.154.202.0 59.154.202.0 -- http://mail.python.org/mailman/listinfo/python-list
Re: Super() confusion
On 10 Feb, 20:45, Jean-Paul Calderone exar...@divmod.com wrote: It replaces one kind of repetition with another. I think each kind is about as unpleasant. Has anyone gathered any data on the frequency of changes of base classes as compared to the frequency of classes being renamed? I don't think either happens very often, but it might be interesting to see some numbers. Base class changes are less important than common derived class functionality. For example, I have employed the following style of class hierarchy in at least one system: class ResourceUsingClass: Stuff using some resource, like a file. Should we close the file when we're finished with it? Is that rude? Best not do it! def close(self): pass # Don't close anything! class SelfContainedResourceUsingClass(ResourceUsingClass): We don't care about keeping the resource open in this class. The user of the class should just need to call the close method. def close(self): ResourceUsingClass.close(self) # Now close the resource! I know that there would be other ways of solving this problem, but in this case, for every class we want to subclass and provide such functionality, we need to write a specific close method. With super, we can avoid being specific about the superclass, but we still need to write the method unless we define it in a mix-in which appears before the superclass in the method resolution order. I think this is the only real use I've found for super, mostly because, as you say, in most other situations it doesn't actually save anyone very much effort. Paul -- http://mail.python.org/mailman/listinfo/python-list
Re: Replace unknow string varible in file.
namire wrote: Hey .python first time poster here. I'm pretty good with python so far, but I keep needed a function in my program but not knowing how to build it. =( Here's the problem: Imagine a html file full of 100's of these strings all mooshed together onto many lines; !--@@MARKER@@; id=ITEM--ITEMbr Where the word 'MARKER' is a constant, it stay the same in each string and the word 'ITEM' is a random combination of ascii characters of an unknown length. So for example a: !--@@MARKER@@; id=CATFISH--CATFISHbrh1Text text text/ h1!--@@MARKER@@; id=SPAM--SPAMbr and so on... What I need to do it replace each instance of the random letter with a constant and/or delete them. The file is a html file so the stuff inside of !-- -- is ok to keep I cannot understand what you want to do where. The last phrase implies 'leave the comments alone' but you only talked about random letters within the comments. I suggest a minimal but complete example of possible input and desired output. and I need that data to identify where the strings are in the file (it's full of other stuff too). I'm tired making a bruteforcer but with unknown length and 26 letters of the alphabet I gave up because it would take too long (it was something like; read file; if '@@MARKER@@; id='+str(gen_string)+'-- +sr(gen_string)+'br' in file then replace with '', but I'm paraphrasing code and it's not the best solution anyway). Just as a comparison in the Windows OS this seems easy to do when managing files, say for the file a-blah-b-blah.tmp where blah is an unknown you can use: del a-*-b-*.tmp to get rid of that file. But for python and a string in text file I don't have a clue. @_@ could someone please help me? -- http://mail.python.org/mailman/listinfo/python-list -- http://mail.python.org/mailman/listinfo/python-list
Re: zlib interface semi-broken
On Tue, Feb 10, 2009 at 01:36:21PM -0800, Scott David Daniels wrote: A simple way to fix this would be to add a finished attribute to the Decompress object. Perhaps you could submit a patch with such a change? Yes, I will try and get to that this week. However, perhaps this would be a good time to discuss how this library works; it is somewhat awkward and perhaps there are other changes which would make it cleaner. Well, it might be improvable, I haven't really looked. I personally would like it and bz2 to get closer to each other in interface, rather than to spread out. SO if you are really opening up a can of worms, I vote for two cans. Well, I like this idea; perhaps this is a good time to discuss the equivalent of some abstract base classes, or interfaces, for compression. As I see it, the fundamental abstractions are the stream-oriented de/compression routines. Given those, one should easily be able to implement one-shot de/compression of strings. In fact, that is the way that zlib is implemented; the base functions are the stream-oriented ones and there is a layer on top of convenience functions that do one-shot compression and decompression. After examining the bz2 module, I notice that it has a file-like interface called bz2file, which is roughly analogous to the gzip module. That file interface could form a third API, and basically conform to what python expects of files. So what I suggest is a common framework of three APIs; a sequential compression/decompression API for streams, a layer (potentially generic) on top of those for strings/buffers, and a third API for file-like access. Presumably the file-like access can be implemented on top of the sequential API as well. If the sequential de/compression routines are indeed primitive, and sufficient for the implementation of the other two APIs, then that gives us the option of implementing the other upper two layers in pure python, potentially simplifying the amount of extension code that has to be written. I see that as desirable, since it gives us options for writing the upper two layers; in pure python, or by writing extensions to the C code where available. I seem to recall a number of ancilliary functions in zlib, such as those for loading a compression dictionary. There are also options such as flushing the compression in order to be able to resynchronize should part of the archive become garbled. Where these functions are available, they could be implemented, though it would be desirable to give them the same name in each module to allow client code to test for their existence in a compression-agnostic way. For what it's worth, I would rather see a pythonic interface to the libraries than a simple-as-can-be wrapper around the C functions. I personally find it annoying to have to drop down to non-OOP styles in a python program in order to use a C library. It doesn't matter to me whether the OOP layer is added atop the C library in pure python or in the C-to-python binding; that is an implementation detail to me, and I suspect to most python programmers. They don't care, they just want it easy to use from python. If performance turns out to matter, and the underlying compression library supports an upper layer in C, then we have the option for using that code. So my suggestion is that we (the python users) brainstorm on how we want the API to look, and not focus on the underlying library except insofar as it informs our discussion of the proper APIs - for example, features such as flushing state, setting compression levels/windows, or for resynchronization points. My further suggestion is that we start with the sequential de/compression, since it seems like a fundamental primitive. De/compressing strings will be trivial, and the file-like interface is already described by Python. So my first suggestion on the stream de/compression API thread is: The sequential de/compression needs to be capable of returning more than just the de/compressed data. It should at least be capable of returning end-of-stream conditions and possibly other states as well. I see a few ways of implementing this: 1) The de/compression object holds state in various members such as data input buffers, data output buffers, and a state for indicating states such as synchronization points or end-of-stream states. Member functions are called and primarily manipulate the data members of the object. 2) The de/compression object has routines for reading de/compressed data and states such as end-of-stream or resynchronization points as exceptions, much like the file class can throw EOFError. My problem with this is that client code has to be cognizant of the possible exceptions that might be thrown, and so one cannot easily add new exceptions should the need arise. For example, if we add an exception to indicate a possible resynchronization point, client code may not be capable of handling it as a non-fatal exception. Thoughts? --
Re: Scanning a file character by character
On Tue, 10 Feb 2009 16:46:30 -0600, Tim Chase wrote: Or for a slightly less simple minded splitting you could try re.split: re.split((\w+), The quick brown fox jumps, and falls over.)[1::2] ['The', 'quick', 'brown', 'fox', 'jumps', 'and', 'falls', 'over'] Perhaps I'm missing something, but the above regex does the exact same thing as line.split() except it is significantly slower and harder to read. ... Note the difference in jumps vs. jumps, (extra comma in the string.split() version) and likewise the period after over. Thus not quite the exact same thing as line.split(). Um... yes. I'll just slink away quietly now... nothing to see here... -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Re: Scanning a file character by character
Steven D'Aprano wrote: On Tue, 10 Feb 2009 16:46:30 -0600, Tim Chase wrote: Or for a slightly less simple minded splitting you could try re.split: re.split((\w+), The quick brown fox jumps, and falls over.)[1::2] ['The', 'quick', 'brown', 'fox', 'jumps', 'and', 'falls', 'over'] Perhaps I'm missing something, but the above regex does the exact same thing as line.split() except it is significantly slower and harder to read. ... Note the difference in jumps vs. jumps, (extra comma in the string.split() version) and likewise the period after over. Thus not quite the exact same thing as line.split(). Um... yes. I'll just slink away quietly now... nothing to see here... You could've used str.translate to strip out the unwanted characters. -- http://mail.python.org/mailman/listinfo/python-list
embedding Python in a shared library
I have embedded Python in a shared library. This works fine in Windows (dll), but I get the following error is Ubuntu when I try to load modules: /usr/lib/python2.5/lib-dynload/*time.so*: error: symbol lookup error: * undefined* symbol: PyExc_ValueError I found many postings on this issue on the internet, but I was not able to find a solution that worked. I tried to load libpython2.5.so.1 into my program using dlopen, but that crashed the program for some reason. I tried building my library using the libpython2.5.a, but the same error was there. I am sure someone has a solution to this, since it seems like a general issue. -- http://mail.python.org/mailman/listinfo/python-list
Re: optparse versus getopt
its a debian package. 2.5 importing optparse works with interactive python, but not through the jython interpreter i an using. is there some way i can force the import based on the the absolute path to the module? On Tue, Feb 10, 2009 at 1:48 PM, Robert Kern robert.k...@gmail.com wrote: On 2009-02-10 15:42, Matthew Sacks wrote: it seems as if optparse isn't in my standard library. How did you install your Python? It has been part of the standard library for a very long time. is there a way to add a lib like ruby gems? http://docs.python.org/install/index.html But optparse (named Optik when it was a separate package) has not been distributed separately from Python for a long time. -- Robert Kern I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth. -- Umberto Eco -- http://mail.python.org/mailman/listinfo/python-list -- http://mail.python.org/mailman/listinfo/python-list
Re: optparse versus getopt
On 2009-02-10 17:32, Matthew Sacks wrote: its a debian package. 2.5 importing optparse works with interactive python, but not through the jython interpreter i an using. Ah, yes. The current version of Jython is still based off of Python 2.2 whereas optparse was introduced in Python 2.3. is there some way i can force the import based on the the absolute path to the module? Better would be for you to copy the optparse.py module onto your Jython's import path. I'm not particularly familiar with the details of Jython, so you will need to consult with the Jython documentation unless if a Jython expert can jump in here. Here is one message describing this procedure: http://osdir.com/ml/lang.jython.user/2004-01/msg00086.html You may want to ask Jython specific questions on the Jython mailing list. You will probably get more on-target answers faster there. -- Robert Kern I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth. -- Umberto Eco -- http://mail.python.org/mailman/listinfo/python-list
Re: Functional schmunctional...
bearophileh...@lycos.com wrote:
Here a small benchmark:
def ip2inet01(a): # can't be used with 6
li = a.split('.')
snip
Wow, thanks everybody for all the suggestions, v.interesting esp as I
didn't even ask for any suggestions! This is a fantastically didactic
newsgroup: you start off just musing about functional programming, you
end up learning python has a rich set of augmented assignment operators,
brilliant :-)
Roger Heathcote.
--
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Re: zlib interface semi-broken
Scott David Daniels scott.dani...@acm.org writes: I suspect that is why such an interface never came up (If you can clone states, then you can say: compress this, then use the resultant state to compress/decompress others. The zlib C interface supports something like that. It is just not exported to the python application. It should be. -- http://mail.python.org/mailman/listinfo/python-list
Escaping my own chroot...
I'm writing a linux remastering script in python where I need to chroot into a folder, run some system commands and then come out and do some tidying up, un-mounting proc sys etc. I got in there with os.chroot() and I tried using that to get back out but that didn't work so... is my script trapped in there forever now or is there an un-hacky way to escape? If it is an OS restriction rather than my ignorance of python is there a canonical way of dealing with it? Should I maybe fork a process, have it do the chroot and wait for it to terminate before continuing? Apologies if this turn out to be OT! Roger. -- http://mail.python.org/mailman/listinfo/python-list
Re: pySerial help please!
On Feb 10, 5:41 pm, Diez B. Roggisch de...@nospam.web.de wrote: bmasch...@gmail.com schrieb: Hello all, I am very new to Python and I am using it because I needed an easy language to control a piece of equipment that connects to my computer via a serial cable. I am running Python 2.6 with pySerial 2.4 under Windows. I can get Python to create a serial port on COM1, but when I try to write to the device, nothing happens. Here is an example: import serial ser = serial.Serial(0) ser.write(otpm 2 16 0) ser.close() If I connect to the device in Hyperterminal the device will behave as expected when I give it the command 'otpm 2 16 0' but not in Python. I have confirmed Python is actually controlling the port because Hyperterminal will not open the port while Python has it open, although I have not been able to try a loopback connector as of yet. Any suggestions out there? Thanks in advance! You need to give a newline, you press return on the terminal as well, don't you? Diez- Hide quoted text - - Show quoted text - Yes! That was exactly the problem. I replaced ser.write(otpm x x x) to (otpm x x x\n) and it WORKS!! Thank you! -- http://mail.python.org/mailman/listinfo/python-list
Re: re.sub and named groups
In article 4c7158d2-5663-46b9-b950-be81bd799...@z6g2000pre.googlegroups.com, Emanuele D'Arrigo man...@gmail.com wrote: I'm having a ball with the power of regular expression but I stumbled on something I don't quite understand: Book recommendation: _Mastering Regular Expressions_, Jeffrey Friedl -- Aahz (a...@pythoncraft.com) * http://www.pythoncraft.com/ Weinberg's Second Law: If builders built buildings the way programmers wrote programs, then the first woodpecker that came along would destroy civilization. -- http://mail.python.org/mailman/listinfo/python-list
Re: Super() confusion
En Tue, 10 Feb 2009 18:01:53 -0200, Daniel Fetchinson fetchin...@googlemail.com escribió: On 2/9/09, Gabriel Genellina gagsl-...@yahoo.com.ar wrote: En Mon, 09 Feb 2009 23:34:05 -0200, Daniel Fetchinson fetchin...@googlemail.com escribió: Consider whether you really need to use super(). http://fuhm.net/super-harmful/ Because throwing around that link carries about the same amount of information as perl is better than python, my IDE is better than yours, vim rulez!, emacs is cooler than vim, etc, etc. Not at all. It contains accurate and valuable information that isn't available elsewhere. But does not contain other valuable information which would demystify super. If only this source is shown to a person who wants to learn the proper usage of super, the impression he/she gets will be distorted. Why so? At the end there is a best practices recipe that pretty much summarizes the proper usage of super, and AFAIK it's the right way to use it. Don't you agree with any of the conclusions? Example: 1. somebody asks about threading 2. reply comes: there is a GIL! you can't do real threading. Now this reply might be technically more-or-less correct, it is misleading and does not help the poster. An informed discussion of the various solutions that does not involve a rant about the GIL would be very useful though. As I said, the article presents a recipe for super() usage, and I'd consider it very helpful. It's far from just saying super s*cks!, or the GIL s*cks! or something like that. You might want to start with http://www.artima.com/weblogs/viewpost.jsp?thread=236275 ...which, although the author says it was written a long time ago, was not published until less than six months ago, and has very low visibility. You are right, it's not in the documentation. But if somebody asks on c.l.p the appropriate answer, I think, is to point to information such as the one above, and not the misleading harmful essay. According to Google, nobody has menctioned the harmful essay in this group since April 2008 [1], months before Simionato's article were available... So this is the *first* time the reference to the former essay could have been replaced by M.S.' one... don't be so strict! Anyway, the right thing to do, IMHO, is to publish correct and accurate documentation in the main Python site. Not everybody knows about this group existence, nor has the time/experience/interest on subscribe here, post a question and wait for an answer. I've seen some posts in python-dev saying something like this is confusing, we should evangelize people on c.l.p. on the right way to do it and I completely disagree; the right place for such things is the product documentation, or -to a much lesser degree because it's online only- some article collection linked from the main site (like the Other resources left bar, already present). Honestly, I don't understand how this thing got so much out of control. If anyone starts an intelligent question or remark about super, this essay is thrown in no matter what. Anyone can explain why? Because for a very loong time (seven years, 2001-2008) super was almost undocumented. The Library Reference -before release 2.6- only had a short paragraph, the [...] You are right, the documentation needs some work in this regard. But again, just because some sources are not in the documentation doesn't mean that the most opinionated essay is the best source. A little search turns up much more useful ones. (not according to Google [2]: I get the harmful article in the top, the thread in python-dev, a couple threads in c.l.p including posts by M.S., his article in artima, and nothing more relevant than Monty Python Super Star up to the 3rd page) *Now* that *I* am aware of the recent article series by M.S., the next time someone asks *me* about super(), probably I'll refer her to both M.S. and J.K.'s articles. Last time I checked (perhaps one or two years ago), the harmful article was almost the only relevant source of info about super(). [1] http://groups.google.com/group/comp.lang.python/search?q=super+harmfulstart=0scoring=d; [2] http://www.google.com/search?q=python+super -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
relocation R_X86_64_32 against `a local symbol' can not be used when making a shared object; recompile with -fPIC
Found a couple of references to this in the newsgroup, but no solutions. I'm trying to build libsbml-3.3.0 with python 2.5.4 support on RHEL 5.3. This RedHat distro has python 2.4.5, and libsbml builds ok with that release. After building 2.5.4 (./configure CFLAGS=-fPIC , as the error message suggests), ld still croaks here: g++ -L../../ -L/usr/local/lib/python2.5/config -shared -o _libsbml.so libsbml_wrap.o -lsbml -lpython2.5 -lxml2 -lz -lm -lm -lz -lbz2 /usr/bin/ld: /usr/local/lib/python2.5/config/libpython2.5.a (abstract.o): relocation R_X86_64_32 against `a local symbol' can not be used when making a shared object; recompile with -fPIC /usr/local/lib/python2.5/config/libpython2.5.a: could not read symbols: Bad value collect2: ld returned 1 exit status Help appreciated -- http://mail.python.org/mailman/listinfo/python-list
Propagating function calls
Suppose I have a python object X, which holds inside it a python object Y. How can I propagate each function call to X so the same function call in Y will be called, i.e: X.doThatFunkyFunk() Would cause Y.doThatFunkyFunk() Thanks, Noam -- http://mail.python.org/mailman/listinfo/python-list
Re: Functional schmunctional...
This is a fantastically didactic newsgroup: you start off just musing about fill-in-the-blank, you end up learning python has some great feature, brilliant :-) +1 !! Malcolm -- http://mail.python.org/mailman/listinfo/python-list
Re: Propagating function calls
On Tue, Feb 10, 2009 at 5:02 PM, Noam Aigerman no...@answers.com wrote: Suppose I have a python object X, which holds inside it a python object Y. How can I propagate each function call to X so the same function call in Y That'd be a method call actually, not a function call. will be called, i.e: X.doThatFunkyFunk() Would cause Y.doThatFunkyFunk() Use a simple proxy (this will forward attribute accesses too, but that doesn't usually matter and can be worked around if necessary): class Delegator(object): def __init__(self, delegate): self.delegate = delegate def __getattr__(self, attr): return getattr(self.delegate, attr) Example: a=Delegator([]) a.append(5) a.delegate [5] Note that this won't forward the operator special methods (e.g. __add__). Cheers, Chris -- Follow the path of the Iguana... http://rebertia.com -- http://mail.python.org/mailman/listinfo/python-list
getopt
if anyone can have a look at this code and offer suggestions i would appreciate it. i am forced to use getopt, so i cant use something good like optparse passedArgs = sys.argv[1:] optlist, args = getopt.getopt(str(passedArgs), [connectPassword=, adminServerURL=, action=, targets=, appDir=]) for some reason this does not work in assigning args to opts. i want to take all of the command line options and assign them to strings here is how i am currently going about it for o,a in optlist: if o == --connectPassword: connectPassword = a print Connect password assigned as + a continue elif o == --adminServerURL: adminServerURL = a print adminServerURL + a continue else: print No connection Arguments Specified TIV -- http://mail.python.org/mailman/listinfo/python-list
Re: Propagating function calls
On Wed, Feb 11, 2009 at 11:02 AM, Noam Aigerman no...@answers.com wrote: Suppose I have a python object X, which holds inside it a python object Y. How can I propagate each function call to X so the same function call in Y will be called, i.e: X.doThatFunkyFunk() Would cause Y.doThatFunkyFunk() Noam, using circuits [1] you could do this: from circuits import Event, Component, Manager class X(Component): def doThatFunkyFunk(self): ... class Y(Component): def doThatFunkyFunk(self): ... manager = Manager() manager += X() manager += Y() manager.send(Event(), doThatFunkyFunk) cheers James [1] http://pypi.python.org/pypi/circuits/ -- http://mail.python.org/mailman/listinfo/python-list
Re: getopt
On Feb 11, 12:12 pm, Matthew Sacks ntw...@gmail.com wrote: if anyone can have a look at this code and offer suggestions i would appreciate it. i am forced to use getopt, so i cant use something good like optparse passedArgs = sys.argv[1:] optlist, args = getopt.getopt(str(passedArgs), [connectPassword=, Dunno where you acquired the str() ... just lose it. Consider checking with the documentation when something does not work. adminServerURL=, action=, targets=, appDir=]) for some reason this does not work in assigning args to opts. -- http://mail.python.org/mailman/listinfo/python-list
Re: Upgrade 2.6 to 3.0
In article 2ba4f763-79fa-423e-b082-f9de829ae...@i20g2000prf.googlegroups.com, Giampaolo Rodola' gne...@gmail.com wrote: Just out of curiosity, am I the only one who think that switching to 3.x right now is not a good idea? Hardly. I certainly wouldn't consider it for production software, but installing it to play with probably is a Good Idea -- it's the future, after all. -- Aahz (a...@pythoncraft.com) * http://www.pythoncraft.com/ Weinberg's Second Law: If builders built buildings the way programmers wrote programs, then the first woodpecker that came along would destroy civilization. -- http://mail.python.org/mailman/listinfo/python-list
Avoiding argument checking in recursive calls
I sometimes write recursive functions like this simple factorial: def fact(n): if n 0: raise ValueError if n = 0: return 1 return fact(n-1)*n At the risk of premature optimization, I wonder if there is an idiom for avoiding the unnecessary test for n = 0 in the subsequent recursive calls? For the sake of the argument, let's pretend the test is expensive and I have a good reason for wanting to avoid it on subsequent calls :) I've done this: def _fact(n): if n = 0: return 1 return _fact(n-1)*n def fact(n): if n 0: raise ValueError return _fact(n) but that's ugly. What else can I do? -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Re: Super() confusion
Consider whether you really need to use super(). http://fuhm.net/super-harmful/ Because throwing around that link carries about the same amount of information as perl is better than python, my IDE is better than yours, vim rulez!, emacs is cooler than vim, etc, etc. Not at all. It contains accurate and valuable information that isn't available elsewhere. But does not contain other valuable information which would demystify super. If only this source is shown to a person who wants to learn the proper usage of super, the impression he/she gets will be distorted. Why so? At the end there is a best practices recipe that pretty much summarizes the proper usage of super, and AFAIK it's the right way to use it. Don't you agree with any of the conclusions? Example: 1. somebody asks about threading 2. reply comes: there is a GIL! you can't do real threading. Now this reply might be technically more-or-less correct, it is misleading and does not help the poster. An informed discussion of the various solutions that does not involve a rant about the GIL would be very useful though. As I said, the article presents a recipe for super() usage, and I'd consider it very helpful. It's far from just saying super s*cks!, or the GIL s*cks! or something like that. You might want to start with http://www.artima.com/weblogs/viewpost.jsp?thread=236275 ...which, although the author says it was written a long time ago, was not published until less than six months ago, and has very low visibility. You are right, it's not in the documentation. But if somebody asks on c.l.p the appropriate answer, I think, is to point to information such as the one above, and not the misleading harmful essay. According to Google, nobody has menctioned the harmful essay in this group since April 2008 [1], months before Simionato's article were available... So this is the *first* time the reference to the former essay could have been replaced by M.S.' one... don't be so strict! Anyway, the right thing to do, IMHO, is to publish correct and accurate documentation in the main Python site. Not everybody knows about this group existence, nor has the time/experience/interest on subscribe here, post a question and wait for an answer. I've seen some posts in python-dev saying something like this is confusing, we should evangelize people on c.l.p. on the right way to do it and I completely disagree; the right place for such things is the product documentation, or -to a much lesser degree because it's online only- some article collection linked from the main site (like the Other resources left bar, already present). Honestly, I don't understand how this thing got so much out of control. If anyone starts an intelligent question or remark about super, this essay is thrown in no matter what. Anyone can explain why? Because for a very loong time (seven years, 2001-2008) super was almost undocumented. The Library Reference -before release 2.6- only had a short paragraph, the [...] You are right, the documentation needs some work in this regard. But again, just because some sources are not in the documentation doesn't mean that the most opinionated essay is the best source. A little search turns up much more useful ones. (not according to Google [2]: I get the harmful article in the top, the thread in python-dev, a couple threads in c.l.p including posts by M.S., his article in artima, and nothing more relevant than Monty Python Super Star up to the 3rd page) *Now* that *I* am aware of the recent article series by M.S., the next time someone asks *me* about super(), probably I'll refer her to both M.S. and J.K.'s articles. Last time I checked (perhaps one or two years ago), the harmful article was almost the only relevant source of info about super(). [1] http://groups.google.com/group/comp.lang.python/search?q=super+harmfulstart=0scoring=d; [2] http://www.google.com/search?q=python+super Okay, I think we converged to a common denominator. I agree with you that the documentation needs additions about super and I also agree with you that referring to both MS and JK articles is appropriate when a question about super comes up. It's good to have a discussion when views actually converge and not diverge at the end :) Cheers, Daniel -- Psss, psss, put it down! - http://www.cafepress.com/putitdown -- http://mail.python.org/mailman/listinfo/python-list
Re: Super() confusion
On Tue, Feb 10, 2009 at 9:25 PM, Daniel Fetchinson fetchin...@googlemail.com wrote: Consider whether you really need to use super(). http://fuhm.net/super-harmful/ Because throwing around that link carries about the same amount of information as perl is better than python, my IDE is better than yours, vim rulez!, emacs is cooler than vim, etc, etc. Not at all. It contains accurate and valuable information that isn't available elsewhere. But does not contain other valuable information which would demystify super. If only this source is shown to a person who wants to learn the proper usage of super, the impression he/she gets will be distorted. Why so? At the end there is a best practices recipe that pretty much summarizes the proper usage of super, and AFAIK it's the right way to use it. Don't you agree with any of the conclusions? Example: 1. somebody asks about threading 2. reply comes: there is a GIL! you can't do real threading. Now this reply might be technically more-or-less correct, it is misleading and does not help the poster. An informed discussion of the various solutions that does not involve a rant about the GIL would be very useful though. As I said, the article presents a recipe for super() usage, and I'd consider it very helpful. It's far from just saying super s*cks!, or the GIL s*cks! or something like that. You might want to start with http://www.artima.com/weblogs/viewpost.jsp?thread=236275 ...which, although the author says it was written a long time ago, was not published until less than six months ago, and has very low visibility. You are right, it's not in the documentation. But if somebody asks on c.l.p the appropriate answer, I think, is to point to information such as the one above, and not the misleading harmful essay. According to Google, nobody has menctioned the harmful essay in this group since April 2008 [1], months before Simionato's article were available... So this is the *first* time the reference to the former essay could have been replaced by M.S.' one... don't be so strict! Anyway, the right thing to do, IMHO, is to publish correct and accurate documentation in the main Python site. Not everybody knows about this group existence, nor has the time/experience/interest on subscribe here, post a question and wait for an answer. I've seen some posts in python-dev saying something like this is confusing, we should evangelize people on c.l.p. on the right way to do it and I completely disagree; the right place for such things is the product documentation, or -to a much lesser degree because it's online only- some article collection linked from the main site (like the Other resources left bar, already present). Honestly, I don't understand how this thing got so much out of control. If anyone starts an intelligent question or remark about super, this essay is thrown in no matter what. Anyone can explain why? Because for a very loong time (seven years, 2001-2008) super was almost undocumented. The Library Reference -before release 2.6- only had a short paragraph, the [...] You are right, the documentation needs some work in this regard. But again, just because some sources are not in the documentation doesn't mean that the most opinionated essay is the best source. A little search turns up much more useful ones. (not according to Google [2]: I get the harmful article in the top, the thread in python-dev, a couple threads in c.l.p including posts by M.S., his article in artima, and nothing more relevant than Monty Python Super Star up to the 3rd page) *Now* that *I* am aware of the recent article series by M.S., the next time someone asks *me* about super(), probably I'll refer her to both M.S. and J.K.'s articles. Last time I checked (perhaps one or two years ago), the harmful article was almost the only relevant source of info about super(). [1] http://groups.google.com/group/comp.lang.python/search?q=super+harmfulstart=0scoring=d; [2] http://www.google.com/search?q=python+super Okay, I think we converged to a common denominator. I agree with you that the documentation needs additions about super and I also agree with you that referring to both MS and JK articles is appropriate when a question about super comes up. It's good to have a discussion when views actually converge and not diverge at the end :) Wait, that's not supposed to happen. This is Usenet after all. Quick, someone comment on the GIL! -- Psss, psss, put it down! - http://www.cafepress.com/putitdown -- http://mail.python.org/mailman/listinfo/python-list -- http://mail.python.org/mailman/listinfo/python-list
Iterable Ctypes Struct
I like the ability to access elements of a struct such as with ctypes Structure: myStruct.elementName1 4 What I like about it is there are no quotes needed. What I don't like about it is that it's not iterable: for n in myStruct: == gives error print n I don't want to force the end user to have preknowledge of the element names. Has anyone subclassed ctypes Structure based class to be iterable? Before a noob starts trying to do this, is it possible? How to approach it? Thx, Mark -- http://mail.python.org/mailman/listinfo/python-list
Re: Avoiding argument checking in recursive calls
I've done this: def _fact(n): if n = 0: return 1 return _fact(n-1)*n def fact(n): if n 0: raise ValueError return _fact(n) but that's ugly. What else can I do? Hello, an idea is optional keyword arguments. def fact(n, check=False): if not check: if n 0: raise ValueError if n == 0: return 1 return fact(n - 1, check=True) * n essentially hiding an expensive check with a cheap one. It saves you duplicating code in a separate function like in your example. -- http://mail.python.org/mailman/listinfo/python-list
Re: pySerial help please!
On 2009-02-10, bmasch...@gmail.com bmasch...@gmail.com wrote: Hello all, I am very new to Python and I am using it because I needed an easy language to control a piece of equipment that connects to my computer via a serial cable. I am running Python 2.6 with pySerial 2.4 under Windows. I can get Python to create a serial port on COM1, but when I try to write to the device, nothing happens. Here is an example: import serial ser = serial.Serial(0) ser.write(otpm 2 16 0) ser.close() Are you sure you don't need some sort of line-terminator (e.g \r or \n) to tell the device to go ahead and execute the command? If I connect to the device in Hyperterminal the device will behave as expected when I give it the command 'otpm 2 16 0' but not in Python. In Hyperterminal did you have to press [enter] to get the command to execute? If you close the port immediately after calling write(), it's possible that the data never actually got sent. You should probably wait until the data has been sent before closing the port. If you're running on Unix, I you should be able to call ser.flush() to wait until the output buffer has been sent. However, I wouldn't count too heavily on the underlying Unix serial driver properly implimenting the tcdrain call. And, I think the flush() call on Windows is a noop. So, putting an appropriate delay between the write and the close is probably the safest thing to do. -- Grant -- http://mail.python.org/mailman/listinfo/python-list
Re: Super() confusion
En Wed, 11 Feb 2009 00:31:06 -0200, Benjamin Kaplan benjamin.kap...@case.edu escribió: On Tue, Feb 10, 2009 at 9:25 PM, Daniel Fetchinson fetchin...@googlemail.com wrote: Okay, I think we converged to a common denominator. I agree with you that the documentation needs additions about super and I also agree with you that referring to both MS and JK articles is appropriate when a question about super comes up. It's good to have a discussion when views actually converge and not diverge at the end :) Wait, that's not supposed to happen. This is Usenet after all. Quick, someone comment on the GIL! Our resident trolls are sleeping, it seems... -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
Difference between vars() and locals() and use case for vars()
Can someone explain the difference between vars() and locals()? I'm also trying to figure out what the use case is for vars(), eg. when does it make sense to use vars() in a program? Thank you, Malcolm -- http://mail.python.org/mailman/listinfo/python-list
Re: Difference between vars() and locals() and use case for vars()
En Wed, 11 Feb 2009 01:38:49 -0200, pyt...@bdurham.com escribió: Can someone explain the difference between vars() and locals()? I'm also trying to figure out what the use case is for vars(), eg. when does it make sense to use vars() in a program? Without arguments, vars() returns the current namespace -- same as locals() inside a function, same as locals() *and* globals() outside any function (i.e., in a module or running in the interactive interpreter) With an argument (that is, vars(x)) it returns the names defined by the object itself; for normal class instances, that means its __dict__ It's useful in the interactive interpreter, to examine some object's contents. Maybe in other special cases. Certainly not in everyday's programming. -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
Re: Difference between vars() and locals() and use case for vars()
Thank you Gabriel! Malcolm - Original message - From: Gabriel Genellina gagsl-...@yahoo.com.ar To: python-list@python.org Date: Wed, 11 Feb 2009 02:04:47 -0200 Subject: Re: Difference between vars() and locals() and use case for vars() En Wed, 11 Feb 2009 01:38:49 -0200, pyt...@bdurham.com escribió: Can someone explain the difference between vars() and locals()? I'm also trying to figure out what the use case is for vars(), eg. when does it make sense to use vars() in a program? Without arguments, vars() returns the current namespace -- same as locals() inside a function, same as locals() *and* globals() outside any function (i.e., in a module or running in the interactive interpreter) With an argument (that is, vars(x)) it returns the names defined by the object itself; for normal class instances, that means its __dict__ It's useful in the interactive interpreter, to examine some object's contents. Maybe in other special cases. Certainly not in everyday's programming. -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list -- http://mail.python.org/mailman/listinfo/python-list
Re: can multi-core improve single funciton?
Hi, guys, my fib(xx) is just an example to show what is a single function and what is the effect I expect to see when enable multi-core. My real purpose is to know whether multi-core can help to improve the speed of a common function. But I know definitely that the answer is NO. -- http://mail.python.org/mailman/listinfo/python-list
Re: Avoiding argument checking in recursive calls
En Tue, 10 Feb 2009 23:58:07 -0200, Steven D'Aprano ste...@remove.this.cybersource.com.au escribió: I sometimes write recursive functions like this simple factorial: def fact(n): if n 0: raise ValueError if n = 0: return 1 return fact(n-1)*n At the risk of premature optimization, I wonder if there is an idiom for avoiding the unnecessary test for n = 0 in the subsequent recursive calls? For the sake of the argument, let's pretend the test is expensive and I have a good reason for wanting to avoid it on subsequent calls :) I've done this: def _fact(n): if n = 0: return 1 return _fact(n-1)*n def fact(n): if n 0: raise ValueError return _fact(n) but that's ugly. What else can I do? I don't think it's ugly; you have an implementation (_fact) and its public interfase (fact). In 'fact' you could check that n is actually an integer (an implicit precondition, your algorithm doesn't finish in other case) and whatever validation is also required. Perhaps its arguments come from user input and you need stricter tests, or convert from other type (like float-int). On the other hand, '_fact' is private and you can assume their arguments are exactly what you require. In Pascal I would have used a nested _fact function; in Python it isn't as efficient so I'd write it as your own example. This is a rather used idiom - in the Python C API, by example, usually you see a public function PyFoo_DoSomething(PyObject* obj) and a private one _PyFoo_DoSomething(double x) (assume a function like sqrt, number - float). The public one takes a generic Python object, checks its type, converts it to a C double value, and if all went OK, finally calls the private implementation passing that value. -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
Re: Avoiding argument checking in recursive calls
On Feb 11, 1:48 pm, Jervis Whitley jervi...@gmail.com wrote: Hello, an idea is optional keyword arguments. def fact(n, check=False): if not check: if n 0: raise ValueError if n == 0: return 1 return fact(n - 1, check=True) * n essentially hiding an expensive check with a cheap one. It saves you duplicating code in a separate function like in your example. Given the original read: def fact(n): if n 0: raise ValueError if n = 0: return 1 return fact(n-1)*n You've merely replaced the 'test n0' with 'not check' at the expense of an additional parameter that has to be passed each time (and the additional test 'n0' for the first iteration). -- http://mail.python.org/mailman/listinfo/python-list
Re: Super() confusion
On Feb 10, 9:19 am, Gabriel Genellina gagsl-...@yahoo.com.ar wrote: You really should push them to be included in python.org, even in their unfinished form. (At least a link in the wiki pages). Their visibility is almost null now. It looks like I made an unfortunate choice with the title (Things to Know about Super). I have just changed it to Things to Know about *Python* Super so that now googling for python super should hopefully find them. I agree that the real solution would be to publish on python.org, but for that I have to write yet another paper about Python 3.0 super, cut things about old version/bugs of Python, re-read the whole beast, and convince the core developers to publish it (which is not automatic). That is some work, and I have many other projects going on right now. Truth is, discussions about super do not come out so often, and most people don't care. They're very clearly written - I wish you had published them years ago! Me too, but you know what happens when working for free and without deadlines ;) again, you really should publish the series in a more prominent place. Soon or later I will go back to super in Python 3.0, but now I am working on my Scheme series, I have yet to translate two articles of my Mixins considered harmful series, and I have at least two other articles which has been waiting publication for more than one year. Plus, I have a full time job ;) But if you and others keep bugging me something may happen ... Michele Simionato -- http://mail.python.org/mailman/listinfo/python-list
Re: can multi-core improve single funciton?
On Wed, Feb 11, 2009 at 2:21 PM, oyster lepto.pyt...@gmail.com wrote: My real purpose is to know whether multi-core can help to improve the speed of a common function. But I know definitely that the answer is NO. As stated by others, and even myself, it is not possible to just automagically improve the execution speed of a single function - let alone an application. Your problem must be capable of being divided up into work units that can be parallelized. If this is not possible, multiple cores (no matter how many you have) -will not- help you. cheers James -- http://mail.python.org/mailman/listinfo/python-list
Re: can multi-core improve single funciton?
On Tue, Feb 10, 2009 at 8:57 PM, James Mills prolo...@shortcircuit.net.au wrote: On Wed, Feb 11, 2009 at 2:21 PM, oyster lepto.pyt...@gmail.com wrote: My real purpose is to know whether multi-core can help to improve the speed of a common function. But I know definitely that the answer is NO. As stated by others, and even myself, it is not possible to just automagically improve the execution speed of a single function - let alone an application. Your problem must be capable of being divided up into work units that can be parallelized. If this is not possible, multiple cores (no matter how many you have) -will not- help you. See also Amdahl's Law -- http://en.wikipedia.org/wiki/Amdahl%27s_law Cheers, Chris -- Follow the path of the Iguana... http://rebertia.com -- http://mail.python.org/mailman/listinfo/python-list
Re: bool evaluations of generators vs lists
On Tue, 2009-02-10 at 12:50 -0800, Josh Dukes wrote: The thing I don't understand is why a generator that has no iterable values is different from an empty list. Why shouldn't bool == has_value?? Technically a list, a tuple, and a string are also objects but if they lack values they're evaluated as False. It seems to me that a generator is an object that intends to replace lists where lazy evaluation would be more efficent. Here is one place where that's definitely true. Just in case it's not perfectly clear: until you call next() there is no way to know whether the generator will yield any value or not -- and once it does, it's lost until you explicitely save it. This generator doesn't yield any value - but you have to wait for a while if you call .next() on it, until eventually raises StopIteration: (x for x in xrange(20) if x1000) En Tue, 10 Feb 2009 19:25:47 -0200, Albert Hopkins mar...@letterboxes.org escribió: The main reason I'm interested in this is that it improves performance immensely over boolean evaluation of large lists (as the attached code shows). It seems to me if I could use find a good use for it in my experimentation that someone else might also want to do the same thing in real-world code. I don't understand what you mean by this. But if you really want to know if a generator is non-empty: def non_empty(virgin_generator): try: virgin_generator.next() # note you just lost the first value return True except StopIteration: return False The only way to get around this is to put all the values of a generator inside a container (e.g. a list): For a long generator you may not want to do that, also you may not want to lose the next element. A variation of your function above is useful in such cases: py def end_of_gen(g): ... returns (False, next_element) when it exists or (True, None) when it's empty ... try: return False, g.next() ... except StopIteration: return True, None ... py g = (c for c in Python if c in aeiou) py eog, c = end_of_gen(g) py eog False py c 'o' py eog, c = end_of_gen(g) py eog True py c -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
Re: getopt
The documentation leaves lack for want, especially the examples. On Tue, Feb 10, 2009 at 5:25 PM, John Machin sjmac...@lexicon.net wrote: On Feb 11, 12:12 pm, Matthew Sacks ntw...@gmail.com wrote: if anyone can have a look at this code and offer suggestions i would appreciate it. i am forced to use getopt, so i cant use something good like optparse passedArgs = sys.argv[1:] optlist, args = getopt.getopt(str(passedArgs), [connectPassword=, Dunno where you acquired the str() ... just lose it. Consider checking with the documentation when something does not work. adminServerURL=, action=, targets=, appDir=]) for some reason this does not work in assigning args to opts. -- http://mail.python.org/mailman/listinfo/python-list -- http://mail.python.org/mailman/listinfo/python-list
Re: Iterable Ctypes Struct
En Wed, 11 Feb 2009 00:31:26 -0200, mark.sea...@gmail.com escribió:
I like the ability to access elements of a struct such as with ctypes
Structure:
myStruct.elementName1
4
What I like about it is there are no quotes needed.
What I don't like about it is that it's not iterable:
for n in myStruct: == gives error
print n
I don't want to force the end user to have preknowledge of the element
names.
Note that those names are available as the _fields_ class attribute
Has anyone subclassed ctypes Structure based class to be iterable?
Before a noob starts trying to do this, is it possible? How to
approach it?
The easiest way would be to define __getitem__ accepting index 0, 1, 2...
until the last defined field.
See http://docs.python.org/reference/datamodel.html#object.__getitem__
code
from ctypes import Structure
class IterableStructure(Structure):
def __getitem__(self, i):
if not isinstance(i, int):
raise TypeError('subindices must be integers: %r' % i)
return getattr(self, self._fields_[i][0])
/code
This was tested as much as you see here:
py from ctypes import c_int
py
py class POINT(IterableStructure):
... _fields_ = [(x, c_int),
... (y, c_int)]
...
py point = POINT(10, 20)
py print point.x, point.y
10 20
py for field in point:
... print field
...
10
20
py print list(point)
[10, 20]
--
Gabriel Genellina
--
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Re: can multi-core improve single funciton?
oyster lepto.pyt...@gmail.com writes: Hi, guys, my fib(xx) is just an example to show what is a single function and what is the effect I expect to see when enable multi-core. My real purpose is to know whether multi-core can help to improve the speed of a common function. But I know definitely that the answer is NO. Well, it depends on the implementation. Python isn't at the moment designed for using multicores but as it evolves that may change. The blog post http://cgi.cse.unsw.edu.au/~dons/blog/2007/11/29 may be of interest re parallelizing that fibonacci function. -- http://mail.python.org/mailman/listinfo/python-list
Re: getopt
On Feb 11, 12:25 pm, John Machin sjmac...@lexicon.net wrote:
On Feb 11, 12:12 pm, Matthew Sacks ntw...@gmail.com wrote:
if anyone can have a look at this code and offer suggestions i would
appreciate it.
i am forced to use getopt, so i cant use something good like optparse
passedArgs = sys.argv[1:]
optlist, args = getopt.getopt(str(passedArgs), [connectPassword=,
Dunno where you acquired the str() ... just lose it. Consider checking
with the documentation when something does not work.
Rule 2: read further in the documentation than you think you need
to :-)
You have omitted the second arg, the one that defines short options.
As for the second part of your question, assigning to locals is
tedious as you have found. The classical solution is to jam the
options into an object that acts like a 'record' or a 'struct'.
Another possibility is the newfangled 'named tuple'. The following
illustrates working code for getting your optlist going, and using the
'record' idea. Keep on going (next step: add a function for each arg
that will convert the value from str to int/float/bool/etc as/if
appropriate) and you will have rewritten optparse.
HTH,
John
C:\junktype getopt_demo.py
import getopt, sys
long_arg_defns = { # sets up defaults
cp: None,
asu: xyzzy,
act: do_nothing,
tgts:,
ad: 1.23,
}
long_arg_list = [x + '=' for x in long_arg_defns.keys()]
passedArgs = sys.argv[1:]
print 'passedArgs', passedArgs
print '\nattempt 1'
try:
optlist, args = getopt.getopt(str(passedArgs), long_arg_list)
print optlist, args
except Exception, e:
print %s: %s % (e.__class__.__name__, e)
print '\nattempt 2'
try:
optlist, args = getopt.getopt(passedArgs, long_arg_list)
print optlist, args
except Exception, e:
print %s: %s % (e.__class__.__name__, e)
print '\nattempt 3'
try:
optlist, args = getopt.getopt(passedArgs, '', long_arg_list)
print optlist, args
except Exception, e:
print %s: %s % (e.__class__.__name__, e)
class Record(object):
def __init__(self, initial_dict, optlist):
for attr, default in initial_dict.items():
setattr(self, attr, default)
for attr, value in optlist:
setattr(self, attr.lstrip('-'), value)
def __str__(self):
return Record: %s % self.__dict__
r = Record(long_arg_defns, optlist)
print
print r
print
print r.cp, r.act, r.ad
C:\junkgetopt_demo.py --cp xxxcp --ad yad extra1 extra2
passedArgs ['--cp', 'xxxcp', '--ad', 'yad', 'extra1', 'extra2']
attempt 1
[] ['--cp', 'xxxcp', '--ad', 'yad', 'extra1', 'extra2']
attempt 2
GetoptError: option --cp not recognized
attempt 3
[('--cp', 'xxxcp'), ('--ad', 'yad')] ['extra1', 'extra2']
Record: {'tgts': '', 'cp': 'xxxcp', 'ad': 'yad', 'asu': 'xyzzy',
'act': 'do _nothing'}
xxxcp do_nothing yad
C:\junk
--
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Re: python3 tutorial for newbie
En Tue, 10 Feb 2009 16:22:36 -0200, Gary Wood python...@sky.com escribió: Can someone recommend a good tutorial for Python 3, ideally that has tasks or assignments at the end of each chapter. I don't know of any specifically targetted to Python 3, except the official one at http://www.python.org/doc/3.0/ For the most part, any Python tutorial should be fine. Perhaps the only visible change (at the tutorial level) is that print became a function: # 2.x syntax: print Hello, world! # 3.x syntax: print(Hello, world!) That said, Python 3.0 is so recent that isn't widely used yet, and many third party libraries aren't available for 3.0 at this moment. This certainly will change in the future, but in the meantime, perhaps you should stick to Python 2.6 for a while. -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
Re: getopt
On Feb 11, 4:36 pm, Matthew Sacks ntw...@gmail.com wrote: The documentation leaves lack for want, especially the examples. You had two problems: (1) str(passedArgs): The docs make it plain that args is a list, not a str instance: args is the argument list to be parsed, without the leading reference to the running program. Typically, this means sys.argv[1:]. The 1st and 2nd examples spell out the same story; here's the 2nd: Using long option names is equally easy: s = '--condition=foo --testing --output-file abc.def -x a1 a2' args = s.split() args ['--condition=foo', '--testing', '--output-file', 'abc.def', '-x', 'a1', 'a2'] (2) omitting the *required* options arg: (a) it's not wrapped in [] so it's required (b) the docs say To accept only long options, options should be an empty string. IOW, it may leave lack for want, but not in the areas causing you a bother. -- http://mail.python.org/mailman/listinfo/python-list
Browse Dialog
Hi , I am using TKinter for creating a GUI. As of now i am using tkFileDialog module for selection of file/directory.But i see that i can use either of these at one go.Is there a way i can select a file or a directory through a single dialog box?? -- http://mail.python.org/mailman/listinfo/python-list
Programmatically changing network proxy settings on the Mac
Hi, Anybody have suggestions of how network proxy settings can be changed programmatically on the Mac, Tiger and Leopard. Are there any helpful python api's that can be used. Thanks Sunil -- http://mail.python.org/mailman/listinfo/python-list
Re: python3 tutorial for newbie
http://wiki.python.org/moin/Python3.0Tutorials On Wed, Feb 11, 2009 at 3:22 AM, Gary Wood python...@sky.com wrote: Can someone recommend a good tutorial for Python 3, ideally that has tasks or assignments at the end of each chapter. Please, -- http://mail.python.org/mailman/listinfo/python-list -- http://mail.python.org/mailman/listinfo/python-list
Re: getopt
I didn't realize that the no-value arguments, -b, -h, etc are required? This seems to make things a bit more difficult considering unless I use the GNU style getopt all arguments are required to be passed? I could be mistaken. I will have a look at what you have posted here and report my results. I appreciate the response. M On Tue, Feb 10, 2009 at 10:36 PM, John Machin sjmac...@lexicon.net wrote: On Feb 11, 4:36 pm, Matthew Sacks ntw...@gmail.com wrote: The documentation leaves lack for want, especially the examples. You had two problems: (1) str(passedArgs): The docs make it plain that args is a list, not a str instance: args is the argument list to be parsed, without the leading reference to the running program. Typically, this means sys.argv[1:]. The 1st and 2nd examples spell out the same story; here's the 2nd: Using long option names is equally easy: s = '--condition=foo --testing --output-file abc.def -x a1 a2' args = s.split() args ['--condition=foo', '--testing', '--output-file', 'abc.def', '-x', 'a1', 'a2'] (2) omitting the *required* options arg: (a) it's not wrapped in [] so it's required (b) the docs say To accept only long options, options should be an empty string. IOW, it may leave lack for want, but not in the areas causing you a bother. -- http://mail.python.org/mailman/listinfo/python-list -- http://mail.python.org/mailman/listinfo/python-list
Re: Avoiding argument checking in recursive calls
Steven D'Aprano wrote: I sometimes write recursive functions like this simple factorial: def fact(n): if n 0: raise ValueError if n = 0: return 1 return fact(n-1)*n At the risk of premature optimization, I wonder if there is an idiom for avoiding the unnecessary test for n = 0 in the subsequent recursive calls? For the sake of the argument, let's pretend the test is expensive and I have a good reason for wanting to avoid it on subsequent calls :) How about: def fact(n): if n 2: if n 0: raise ValueError return 1 return fact(n - 1) * n But really, iteration is the solution to this, and avoiding the right answer is a mistake. I couldn't resist fixing your test so you do one less layer of recursion. --Scott David Daniels scott.dani...@acm.org -- http://mail.python.org/mailman/listinfo/python-list
Re: Avoiding argument checking in recursive calls
Steven D'Aprano ste...@remove.this.cybersource.com.au writes: def fact(n): if n 0: raise ValueError if n = 0: return 1 return fact(n-1)*n At the risk of premature optimization, I wonder if there is an idiom for avoiding the unnecessary test for n = 0 in the subsequent recursive calls? I'd write nested functions: def fact(n): if n 0: raise ValueError def f1(n): return 1 if n==0 else n*f1(n-1) return f1(n) If the language implementation supports tail recursion optimization there's an accumulation-parameter style that takes a little getting used to but is familiar in functional programming: def fact(n): if n 0: raise ValueError def f1(k,n): return k if n==0 else f1(k*n, n-1) return f1(1, n) This won't do any good in CPython but maybe PyPy or Pyrex or whatever can make use of it. In this case the nested function is already there, and the n0 check naturally lifts out of it. -- http://mail.python.org/mailman/listinfo/python-list
Re: Avoiding argument checking in recursive calls
Paul Rubin http://phr...@nospam.invalid writes: I'd write nested functions: def fact(n): if n 0: raise ValueError def f1(n): return 1 if n==0 else n*f1(n-1) return f1(n) I forgot to add: all these versions except your original one should add a type check if you are trying to program defensively. Otherwise they can recurse infinitely if you give a positive non-integer arg like fact(3.5). -- http://mail.python.org/mailman/listinfo/python-list
[issue4804] Python on Windows disables all C runtime library assertions
Martin v. Löwis mar...@v.loewis.de added the comment: The revised patch looks fine to me, please apply. ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue4804 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5200] unicode.normalize gives wrong result for some characters
New submission from Peter Landgren peter.tal...@telia.com: If any of the Swedish characters åäöÅÄÖ are input to unicode.normalize(form, ustr) with form = NFD or NFKD the result will be aaoAAO. åäöÅÄÖ are normal character and should be the same after normalize. They are not connected to aaoAAO other than for historic reasons, but not in modern languages. It's a common misinterpretation that the dots and circle above them are diacritic signs, but those letters should behave as the (Danish) Ø which is normalized correctly. From Wikipedia: Å is often perceived as an A with a ring, interpreting the ring as a diacritical mark. However, in the languages that use it, the ring is not considered a diacritic but part of the letter. The letter Ö in the Swedish and Icelandic alphabets historically arises from the Germanic umlaut, but it is considered a separate letter from O. See http://en.wikipedia.org/wiki/%C3%85 I think this is pobably impossible to solve as it will be mixed up with umlaut and you don't know what language the specific word is connected to. -- components: Library (Lib) messages: 81536 nosy: PeterL severity: normal status: open title: unicode.normalize gives wrong result for some characters type: behavior versions: Python 2.5 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5200 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue1818] Add named tuple reader to CSV module
Jervis Whitley jervi...@gmail.com added the comment: Updated NamedTupleReader to give a rename=False keyword argument. rename is passed directly to the namedtuple factory function to enable automatic handling of invalid fieldnames. Two new tests for the rename keyword. Cheers, Added file: http://bugs.python.org/file13009/ntreader4.diff ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue1818 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5201] Using LDFLAGS='-rpath=\$$LIB:/some/other/path' ./configure breaks the build
New submission from Floris Bruynooghe floris.bruynoo...@gmail.com: When specifying an RPATH with -rpath or -R you can use the special tokens `$LIB' and `$ORIGIN' which the runtime linker interprets as normal search path and relative to current sofile respectively. To get these correctly to the gcc command line you need to specify this in LDFLAGS as `\$$LIB' to work around escapes of both the makefile and shell, so in the Python Makefile this will appear somewhere as (this is on one line): CONFIG_ARGS= '--prefix=/opt/example.com/python25' 'LDFLAGS=-Wl,-rpath=\$$LIB:/opt/example.com/lib,--enable-new-dtags' This works for compiling the main python binary. But when the extension modules get compiled distutils chokes on this. distutils.sysconfig.parse_makefile() does think that any value of a variable that contains `$' in it refers to an other variable in the makefile. It will fail to find the value and CONFIG_ARGS will not be defined. This then fails in setup.py for the _ctypes extension: if not '--with-system-ffi' in sysconfig.get_config_var(CONFIG_ARGS): return Where `None' is returned instead of a list by .get_config_var(). It seems that distutils.sysconfig.parse_makefile() needs to understand more of the makefile synatax to deal with this. -- assignee: tarek components: Distutils messages: 81538 nosy: flub, tarek severity: normal status: open title: Using LDFLAGS='-rpath=\$$LIB:/some/other/path' ./configure breaks the build type: compile error versions: Python 2.5, Python 2.6, Python 2.7, Python 3.0 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5201 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5202] wave.py cannot write wave files into a shell pipeline
New submission from David Jones d...@pobox.com: When using the wave module to output wave files, the output file cannot be a Unix pipeline. Example. The following program outputs a (trivial) wave file on stdout: #!/usr/bin/env python import sys import wave w = wave.open(sys.stdout, 'w') w.setnchannels(1) w.setsampwidth(1) w.setframerate(32000) w.setnframes(0) w.close() It can create a wave file like this: $ ./bugex foo.wav When used in a pipeline we get: $ ./bugex | wc Traceback (most recent call last): File ./bugex, line 9, in module w.close() File /Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/wave.py , line 437, in close self._ensure_header_written(0) File /Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/wave.py , line 458, in _ensure_header_written self._write_header(datasize) File /Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/wave.py , line 465, in _write_header self._form_length_pos = self._file.tell() IOError: [Errno 29] Illegal seek Exception exceptions.IOError: (29, 'Illegal seek') in bound method Wave_write.__del__ of wave.Wave_write instance at 0x71418 ignored 0 1 8 The wave module has almost all it needs to work around this problem. The wave module will only seek the output if it needs to patch the header. If you use setnframes to write the correct number of frames before writing them with writeframesraw then the header will not be patched upon calling close. However... The problem is that the tell method is invoked on the output stream (to record where the header is, in the event that we need to patch it); the tell method fails with an exception when the output is a pipeline (see example, above). Exceptions from tell when writing the header initially (in _write_header) should be ignored. If _patchheader is later invoked it will fail due to lack of pos. -- components: Library (Lib) messages: 81539 nosy: drj severity: normal status: open title: wave.py cannot write wave files into a shell pipeline type: behavior versions: Python 2.5, Python 2.6 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5202 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5175] negative PyLong - C unsigned integral, TypeError or OverflowError?
Lisandro Dalcin dalc...@gmail.com added the comment: Mark, here you have a patch. I've only 'make test' on a 32bit Linux box Just two comments: - in docs: perhaps the 'versionchanged' stuff should be added. - in tests: I did not touch Modules/_testcapimodule.c, as it seems the test is covered. However, note that in all these tests, actual exception types are not checked) -- keywords: +patch Added file: http://bugs.python.org/file13010/negative-to-unsigned.diff ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5175 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
