Re: Test for Pythonwin?
On Jul 31, 2:09 am, steve st...@nospam.au wrote: Is there a good way to check if a script is running inside Pythonwin? Perhaps a property or method that is exposed by that environment? I've used if sys.stdin.fileno() 0: This is not precisely a test for pythonwin, but indicates whether standard streams are available, which is usually what I really want to know. -- http://mail.python.org/mailman/listinfo/python-list
Re: Newbie question about tuples and list comprehensions
First, I second Matt's comment about using a boring old for loop when it is the simplest way to express what you want to do. Being Pythonic is not about using exotic features to scrunch your code down to a cool one-liner. It is about expressing your intentions in a simple, direct way. Sometimes comprehensions, generators, etc. help. Sometimes they only obfuscate. That said, the *most* Pythonic way to do something is to find the existing library that already does it. Check out the Image.point() function in the PIL documentation. You may not need to convert the image to a list at all. - Roger -- http://mail.python.org/mailman/listinfo/python-list
Re: Separators inside a var name
On Jun 9, 7:29 am, Rainy [EMAIL PROTECTED] wrote: ... Another question I have is what other languages allow this naming scheme? The most widely used such language would probably be COBOL, where you write things like SUBTRACT DISCOUNT FROM LIST-PRICE GIVING AMOUNT-DUE I doubt that syntax would catch on in Python :-) -- http://mail.python.org/mailman/listinfo/python-list
Re: Is there an official way to add methods to an instance?
On Apr 3, 2:57 pm, Brian Vanderburg II [EMAIL PROTECTED] wrote: I've checked out some ways to get this to work. I want to be able to add a new function to an instance of an object. I've tested two different methods that cause problems with 'deleting'/garbage collection (__del__ may never get called), but implemented one sort of hackishly maybe that works find. I'm wondering if there is more of an official way than mine. Maybe I'm missing something, but the boring old straightforward approach works for me: class A: def __del__(self): print Deleting def f(x): print x a = A() a.f = f a.f(42) del a Output: 42 Deleting -- http://mail.python.org/mailman/listinfo/python-list
Re: License of Python
Is there any legal problem with including licenses for languages you don't use? (But I agree with the other posters that any competitor worthy of concern will figure it out in short order if they care.) -- http://mail.python.org/mailman/listinfo/python-list
Re: Naive idiom questions
On Jan 31, 11:48 am, Grant Edwards [EMAIL PROTECTED] wrote: I'm not sure what you're asking. AFAIK, the main reason that strings are immutable is so they can be used as dict keys. I think its more fundamental than that. If strings were mutable you would be constantly worrying about whether changing a string here might affect something there, or whether to write x = y or x = copy.copy(y). Or condsider -- http://mail.python.org/mailman/listinfo/python-list
Re: Ignore exceptions
On Jan 24, 11:30 am, Jonathan Gardner [EMAIL PROTECTED] wrote: A few sample good uses of try/except blocks: (1) Do something else if an expected exception occurs. ... (2) Show a friendly error message when an exception occurs over a significant chunk of the program. (Useful for websites and GUI apps.) ... I'd add (3) Clean-up handlers. These don't actually handle the problem, they just free resources, close files, etc. before re-raising the exception for someone else to worry about. -- http://mail.python.org/mailman/listinfo/python-list
Re: index of min element of sequence
On Jan 21, 8:48 am, Peter Otten [EMAIL PROTECTED] wrote: Neal Becker wrote: What's a good/fast way to find the index of the minimum element of a sequence? ... min(xrange(len(items)), key=items.__getitem__) ... Or just items.index(min(items)) I found this to be significantly faster in a simple test (searching a list of 1000 ints with the minimum in the middle), despite the fact that it requires two passes. I'm sure that one could find cased where Peter's approach is faster, so you if you are concerned about speed you should measure with your own data. -- http://mail.python.org/mailman/listinfo/python-list
Re: Ping Implementation in Python
On Dec 20, 5:41 am, Mrown [EMAIL PROTECTED] wrote: Hi, I was wondering if there was a ping implementation written in Python. http://www.gnist.org/~lars/code/ping/ping.html -- http://mail.python.org/mailman/listinfo/python-list
Re: Determine whether program was started by clicking icon or command line
On Nov 28, 10:51 pm, Benjamin Hell [EMAIL PROTECTED] wrote: Hi! I wonder whether there might be a way to find out how a Python program was started (in my case in Windows): By double clicking the file or by calling it on the DOS command line prompt. Background: I would like to have the program run in an interactive mode if double clicked, and silently in a batch mode when started otherwise. I'm not sure whether this applies to your situation, but often programs started by clicking an icon are run by pythonw, but when started from the command line are run by python. If this is the case sys.stdin.fileno() will return -1 in the former case and 0 in the latter. -- http://mail.python.org/mailman/listinfo/python-list
Re: Limits on search length
Since you are getting the regular expression pattern via an argument I would first check that searchPattern is what you expect. Shells can do funny things with arguments containing special characters. Also, is it possible that the quoted strings in the files contain escapes? For example if a file contains the text hello\n would you consider that 6 characters or 7? -- http://mail.python.org/mailman/listinfo/python-list
Re: A problem with Time
On Aug 16, 9:46 am, MRAB [EMAIL PROTECTED] wrote: As well as the other replies, this also works (as far as I can tell!): import time today = time.localtime() yesterday = today[ : 2] + (today[2] - 1, ) + today[3 : ] yesterday = time.localtime(time.mktime(yesterday)) This is something I have wondered about. The C library mktime function is documented to fix up out of range values,. For example July 32 becomes August 1 and August -1 becomes July 31. Python presumably inherits this very useful (and seemingly not well known) behavior, but it is not documented. Is this just an oversight, or is it intentional on the grounds that it might be platform-dependent? Any language lawyers out there that would care to comment? -- http://mail.python.org/mailman/listinfo/python-list
Re: float to string with different precision
On Aug 10, 8:37 am, Zentrader [EMAIL PROTECTED] wrote: If the above does not work [/code]test_list = [ 5.32, 10.35634, 289.234 ] for num in test_list : str_num = %11.5f % (num) ## expand to at least 5 print str_num, --, str_num.strip()[:5][/code] This has the disadvantage that it doesn't round the last digit. For example 10.356634 yields 10.356 instead of 10.357. You can use '*' in format strings to take a numeric field value from a variable. For example ndecimals = 2 print %5.*f % (ndecimals, x) formats x with 2 digits following the decimal point. Or you can simply cobble up a format string at run time: format = %%5.%df % ndecimals print format % x -- http://mail.python.org/mailman/listinfo/python-list
Re: idiom for RE matching
On Jul 18, 6:52 pm, Gordon Airporte [EMAIL PROTECTED] wrote: ... I've also been assuming that using the re functions that create match objects is slower/heavier than dealing with the simple list returned by findall(). I've profiled it and these matches are the biggest part of the running time of the program, so I really would rather not use anything slower. My guess would be that searching for more matches after finding the first would be more expensive than creating a match object. But that would probably depend on the nature of your data and REs, so you need to test it both ways if you are concerned about performance. It would be nice if findall() had an optional parameter to limit the number of matches, similar to the maxsplit parameter of string.split(). -- http://mail.python.org/mailman/listinfo/python-list
Re: Portable general timestamp format, not 2038-limited
On Jun 22, 10:33 am, James Harris [EMAIL PROTECTED] wrote: I have a requirement to store timestamps in a database. Simple enough you might think but finding a suitably general format is not easy. ... Any thoughts on a better way to do this? (Please reply-all. Thanks). -- James My rule of thumb in situations like this is When in doubt store it as text. The one format I am pretty sure we will still be able to deal with in 2039. - Roger -- http://mail.python.org/mailman/listinfo/python-list
Re: how to do reading of binary files?
On Jun 8, 2:07 am, Diez B. Roggisch [EMAIL PROTECTED] wrote:
...
What has the searching to do with the reading? 10MB easily fit into the
main memory of a decent PC, so just do
contents = open(file).read() # yes I know I should close the file...
print contents.find('\x0c')
Diez
Better make that 'open(file, rb).
--
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Re: Random selection
On May 17, 10:39 pm, Tartifola [EMAIL PROTECTED] wrote: Hi, I have a list with probabilities as elements [p1,p2,p3] with of course p1+p2+p3=1. I'd like to draw a random element from this list, based on the probabilities contained in the list itself, and return its index. Any help on the best way to do that? Thanks This of course depends on your definition of best. There is a fast and simple technique if all probabilities are multiples of 1/n for a reasonably small n, or if you are willing to round them to such. Suppose for example that the probabilities are [0.42, 0.23, 0.35]. Create a list of 100 items with 42 0's, 23 1's, and 35 2's, then select a random element using random.choice() or equivalent. -- http://mail.python.org/mailman/listinfo/python-list
Re: behavior difference for mutable and immutable variable in function definition
On May 4, 12:39 pm, 7stud [EMAIL PROTECTED] wrote: On May 4, 3:30 pm, [EMAIL PROTECTED] wrote: Hi, Can anyone explain the following: Python 2.5 (r25:51908, Apr 9 2007, 11:27:23) [GCC 4.1.1 20060525 (Red Hat 4.1.1-1)] on linux2 Type help, copyright, credits or license for more information. def foo(): ... x = 2 ... foo() def bar(): ... x[2] = 2 ... bar() Traceback (most recent call last): File stdin, line 1, in module File stdin, line 2, in bar NameError: global name 'x' is not defined Thanks, Jianbing The first function is completely irrelevant unless you expect this to work: x = 2 x[2] = 2 Traceback (most recent call last): File test1.py, line 2, in ? x[2] = 2 TypeError: object does not support item assignment So that leaves you with: def bar(): ... x[2] = 2 ... bar() Would you expect this to work: x[2] = 2 print x I will sympathize with the OP to the extent that the message global name 'x' is not defined is a bit misleading. All that the interpreter really knows is that 'x' is not defined, locally or globally, and it should probably not presume to guess the coder's intention. -- http://mail.python.org/mailman/listinfo/python-list
Re: Weird gcc behaviour with function pointer types
On Mar 29, 3:05 am, greg [EMAIL PROTECTED] wrote:
In my quest to eliminate C compiler warnings from
Pyrex output, I've discovered some utterly bizarre
behaviour from gcc 3.3.
The following code:
void g(struct foo *x) {
}
void f(void) {
void (*h)(struct foo *);
h = g;
}
produces the following warning:
blarg.c: In function `f':
blarg.c:6: warning: assignment from incompatible pointer type
However, adding the following line at the top:
typedef struct foo Foo;
makes the warning go away. The mere *presence* of
the typedef is all that's needed -- it doesn't even
have to be used.
This looks like a bug in gcc to me -- what do people
think?
--
Greg
If there is no outer declaration of struct foo visible to both
functions
gcc is right (it usually is when it comes to C technicalities). The
scope
of a struct declared inside a parameter list is limited to the
parameter
list itself, so the two struct foos are technically different types.
Adding the typedef provides a common declaration of struct foo that is
shared by both functions. You don't really even need a typedef; a
global
declaration of just struct foo; should make the problem go away.
I would have expected gcc to also warn you about declaring a struct
inside
a parameter list. Did you get any warnings like that?
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Re: eval('000052') = 42?
On Feb 20, 7:37 pm, John Machin [EMAIL PROTECTED] wrote:
On Feb 21, 3:09 pm, Astan Chee [EMAIL PROTECTED] wrote:
Hi,
I just tried to do
eval('00052') and it returned 42.
Is this a known bug in the eval function? Or have I missed the way eval
function works?
Thanks
Eight fives are forty. Forty plus two is forty two. I see no bug here,
only a language design strangeness which can be blamed on the then-
pervasive influence of all things from Bell Labs :-)
So is this anachronism slated for removal in Python 3?
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Re: why I don't like range/xrange
On Feb 16, 7:01 am, Bart Ogryczak [EMAIL PROTECTED] wrote:
On Feb 16, 4:30 pm, stdazi [EMAIL PROTECTED] wrote:
for (i = 0; some_function() /* or other condition */ ; i++)
C's for(pre,cond,post) code is nothing more, then shorthand form of
pre; while(cond) {code; post;}
I don't disagree with your basic point, but technically this is not
quite true.
Try it with
for (i = 0; i n; i++) {
if (x[i] == 0) continue;
printf(%d\n, x[i]);
}
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wx.Font.GetPointSize returning bogus value?
The following program gets a TextCtrl's text attributes and sets them back unchanged. However it reports that the font size is 124, and after resetting the attributes the text becomes that size. That is, the window displays a normal-size foo and a gigantic bar. Anyone know what's going on? This is WxPython 2.6 on Python 2.5 on Windows XP. -- import sys import wx class MyApp (wx.App): def __init__ (self): wx.App.__init__(self, redirect=0) def OnInit (self): top = wx.Frame(None, size=(500, 300)) txt = wx.TextCtrl(top, -1, foo\n, (-1, -1), (400, 200), wx.TE_RICH|wx.TE_READONLY|wx.TE_MULTILINE) top.Show() attrs = wx.TextAttr() txt.GetStyle(0, attrs) font = attrs.GetFont() print font face, font.GetFaceName() # prints MS Shell Dlg 2 print font family, font.GetFamily() # prints 74 print font size, font.GetPointSize() # prints 124! txt.SetDefaultStyle(attrs) txt.AppendText(bar\n) return True app = MyApp() app.MainLoop() -- http://mail.python.org/mailman/listinfo/python-list
uninstall and Windows file associations
When I installed Python 2.5 (on Windows XP) I left 2.4 in place just in case. Today I decided to remove it. However after doing so (from the control panel) I found that Windows no longer knows about the Python file types and associations. Is this behavior expected, or was there something wrong with my installation? Is there a way to restore the file associations, short of reinstalling 2.5 or manually editing them? -- http://mail.python.org/mailman/listinfo/python-list
pythonw documentation?
I was going to ask how to a program can tell whether it was started by python.exe or pythonw.exe, but after some experimentation I noticed that sys.stdin.fileno() is -1 in the latter case. However on a more general note, the only references to pythonw that I could find in the Python 2.5 documentation are in the Macintosh section. Have I overlooked something, or is this a deficiency that should be addressed? -- http://mail.python.org/mailman/listinfo/python-list
wxPython: wxStaticBitmap and large images
I have a WxPython app that displays images that are typically around 600x600 pixels. I use a wxStaticBitmap, which appears to work fine on Windows XP. However the documentation states that a StaticBitmap ... is meant for display of the small icons in the dialog boxes and is not meant to be a general purpose image display control. In particular, under Windows 9x the size of bitmap is limited to 64*64 pixels and thus you should use your own control if you want to display larger images portably. Assuming that I don't care about Windows 9X, should I be worried? Is there a better way to display images, hopefully without diving down into the device context level? -- http://mail.python.org/mailman/listinfo/python-list
Re: Coding style
Peter Otten wrote: Steve Holden wrote: I'll bet you still write if a3 == True: don't you ;-) I'll second that. if (a3) == True: is the correct way :-) Peter No, to be consistent you'll have to write if ((a3) == True) == True: Oops, I mean, if (((a3) == True) == True) == True: Umm, never mind. -- http://mail.python.org/mailman/listinfo/python-list
Re: zipfile module doesn't allow append
Ritesh Raj Sarraf wrote: The line filename = zipfile.ZipFile(zip_file_name, a) throws an exception if the given filename is not present already. Shouldn't it create a file (in case one is not there) since it is append mode ?? Perhaps it would be nicer that way, but it is working as documented. Catch the exception and open in 'w' mode. To anticipate your next possible problem, note that in append mode if you write a file that already exists in the archive it will not replace the existing file, but will add another one with the same name. As far as I can tell, there is no way to read the newer version because zipfile.read(name) always finds the first version. So if you are trying to update a zipfile you will probably have to read the old archive and write a new one, copying the files you want to keep and replacing the ones you want to update. (At this point you might want to consider invoking an external zip utility instead.) -- http://mail.python.org/mailman/listinfo/python-list
Re: source reduction using Python
[EMAIL PROTECTED] wrote: Intel has introduced something called CESR, written in Python, to aid C, C++, and Fortran programmers in reducing the sizes of programs included in bug reports. Here is a brief description from http://cache-www.intel.com/cd/00/00/21/93/219320_relnotes_10.pdf : ... I think one needs to qualify for Intel Premier Support to get CESR. I wonder if a similar open-source Python program exists. I can't answer your question, but if you are searching it may be helpful to know that the relevant phrase is probably program slicing. -- http://mail.python.org/mailman/listinfo/python-list
Re: Sampling a population
For your example, since the probabilities are all multiples of 0.01 you could make a list of 100 elements. Set one of them to a, 5 of them to b, 50 of them to c, etc. Then just randomly sample from the table (which is O(1)). Of course if the probabilities can be arbitrary floating point values then this won't work. But if you can live with rounding to 3 or 4 digits this is probably the fastest and easiest approach. -- http://mail.python.org/mailman/listinfo/python-list
Re: shuffling elements of a list
Sybren Stuvel wrote: David C Ullrich enlightened us with: I thought that the fact that you could use the same trick for _shuffling_ a list was my idea, gonna make me rich and famous. I guess I'm not the only one who thought of it. Anyway, you can use DSU to _shuffle_ a list by decorating the list with random numbers. This is often done in database queries that need to randomize the data ;-) Sybren -- The problem with the world is stupidity. Not saying there should be a capital punishment for stupidity, but why don't we just take the safety labels off of everything and let the problem solve itself? Frank Zappa DSU seems like a lot of trouble to go through in order to use an O(n log n) sorting algorithm to do what can be done in O(N) with a few lines of code. The core code of random.shuffle() shows how easy it is to do it right: for i in reversed(xrange(1, len(x))): # pick an element in x[:i+1] with which to exchange x[i] j = int(random() * (i+1)) x[i], x[j] = x[j], x[i] -- http://mail.python.org/mailman/listinfo/python-list
Re: Looking for help with Regular Expression
Seem to be a lot of regular expression questions lately. There is a neat little RE demonstrator buried down in Python24/Tools/Scripts/redemo.py, which makes it easy to experiment with regular expressions and immediately see the effect of changes. It would be helpful if it were mentioned in the RE documentation, although I can understand why one might not want a language reference to deal with informally-supported tools. -- http://mail.python.org/mailman/listinfo/python-list
Re: memory error with zipfile module
The basic problem is that the zipfile interface only reads and writes whole files, so it may perform poorly or fail on huge files. At one time I implemented a patch to allow reading files in chunks. However I believe that the current interface has too many problems to solve by incremental patching, and that a zipfile2 module is probably warranted. (Is anyone working on this?) In the meantime I think the best solution is often to just run an external zip/unzip utility to do the heavy lifting. -- http://mail.python.org/mailman/listinfo/python-list
Re: Python trig precision problem
If I were you I would see if I could get the Perl script referred to on the ERIN web page. You might find that the discrepancy is something as simple as a slightly different value for the Earth's radius. And by the way, math.radians() might be a bit clearer than the pi/180 business. -- http://mail.python.org/mailman/listinfo/python-list
Re: Add file to zip, or replace file in zip
First note that zipfile is a plain Python module, so reading Python.../Lib/zipfile.py will reveal all its secrets. I don't think it is possible to replace archive members using the module. You could copy all the files into a new zip file, replacing the ones you want to change as you go. But it might be easier just to use os.system() or something similar to run an external zip program. -- http://mail.python.org/mailman/listinfo/python-list
SEEK_SET defined?
I see that the posixfile module is deprecated. Have the SEEK_SET, etc. constants moved somewhere else, or do I need to define them myself? -- http://mail.python.org/mailman/listinfo/python-list
