🌐 Mailman 3 October 2005 - Python-list - python.org

Why the nonsense number appears?
by Johnny Lee Oct. 31, 2005

Oct. 31, 2005

Hi, Pls take a look at this code: ---------- >>> t1 = "1130748744" >>> t2 = "461" >>> t3 = "1130748744" >>> t4 = "500" >>> time1 = t1+"."+t2 >>> time2 = t3+"."+t4 >>> print time1, time2 1130748744.461 1130748744.500 >>> float(time2) - float(time1) 0.039000034332275391 >>> Why are there so many nonsense tails? thanks for your help. Regards, Johnny

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meschach + Python
by Cyril Bazin Oct. 31, 2005

Oct. 31, 2005

Hello, I need to compute eigenvalues and eigenvectors on sparse matrix. I found a C library "meschach" which seems to do the work. Unfortunatly, this libray doesn't seem to be interfaced in Python. Has anyone ever used this library and interfaced it in Python or has a solution to compute eigenvalues and eigenvalues on sparse matrix efficiently in Python? Thanks in advance, Cyril

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Re: Would there be support for a more general cmp/__cmp__
by Antoon Pardon Oct. 31, 2005

Oct. 31, 2005

Op 2005-10-20, Steve Holden schreef <steve(a)holdenweb.com>: > Antoon Pardon wrote: >> > Ergo: use rich comparisons. rich comparosons can only solve the problem partly. Python does have the cmp function and that can give totaly inconsistent results even when the order defined by the rich comparison functions is consistent but only partial. I think it is a problem if cmp gives me the following results. >>> a1 = foo(1) >>> a2 = foo(2) >>> b1 = foo(1) >>> b2 = foo(2) >>> cmp(a1,b1) 0 >>> cmp(a2,b2) 0 >>> cmp(a1,a2) 1 >>> cmp(b1,a2) 1 >>> cmp(a1,b2) -1 It would be better if cmp would give an indication it can't compare two objects instead of giving incorrect and inconsistent results. -- Antoon Pardon

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Problem with py2exe
by DDany Oct. 31, 2005

Oct. 31, 2005

HI! I've a problem with py2exe: well, first of all I say that I use python 2.4.1 , py2exe 0.6.3 and distutils 1.0.2 on winxp. To use py2exe I wrote a file setup.py like this: from distutils.core import setup import py2exe setup( version = "0.1", description = "Py2Exe Script", name = "App.exe", windows = ["C:\app\\app.py"], ) file that is launched in this way: D:\programs\python24\python.exe setup.py py2exe The command starts and at the beginning seems that all goes on with no problem, but at a certain point there's an error: copying D:\programs\python24\MSVCR71.dll -> D:\Applicazione\dist error: could not delete 'C:\app\dist\MSVCR71.dll': Permission denied However folders build and dist are created: in particular into the folder dist i have the w9xpopen.exe file, some *.pyd files and some dll's... among dll's I have the MSVCR71.dll too. I don't understand what's the problem so I ask you a help!!! See ya, bye!

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Message about not deleted folders using Inno Setup
by Martin Oct. 31, 2005

Oct. 31, 2005

Hi I would like to place a message in an uninstaller window which will inform the user that some folders haven't been deleted. Is that possible using Inno Setup? -- Thanks in advance Martin

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putting a string in Mac Address form
by kyle.tk Oct. 31, 2005

Oct. 31, 2005

I came up with this. Is there a better (more pythonic) way to do it? import string def mac_to_norm(mac): def bad_char(char): if char not in string.hexdigits: return False return True mac = filter(bad_char,mac) if len(mac) is not 12: return None new_mac = '' c = 0 while len(new_mac) < 16: new_mac += mac[c:c+2] + ':' c=c+2 return new_mac[:-1].upper() print mac_to_norm('0012.ab23.b2cd') #shows: 00:12:AB:23:B2:CD The part I think is bad is the while loop part. Could it be better?

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Pickling and unpickling inherited attributes
by Alex Oct. 31, 2005

Oct. 31, 2005

I have a serious problem and I hope there is some solution. It is easier to illustrate with a simple code: >>> class Parent(object): __slots__=['A', 'B'] def __init__(self, a, b): self.A=a; self.B=b def __getstate__(self): return self.A, self.B def __setstate__(self, tup): self.A, self.B=tup >>> class Child(Parent): __slots__=['C',] def __init__(self, c): self.C=c def __getstate__(self): return self.C, def __setstate__(self, tup): self.C, =tup >>> obj=Child(1) >>> obj.A=2 >>> obj.B=3 >>> obj.A 2 >>> obj.B 3 >>> obj.C 1 >>> objct.Z=4 Traceback (most recent call last): File "<pyshell#60>", line 1, in -toplevel- objct.Z=4 AttributeError: 'Child' object has no attribute 'Z' So far so good.. Object obj inherited attributes (A and B) from the parent class and refuses to take any new ones. But look what happens when I try to pickle and unpickle it: >>> import cPickle >>> File=open('test', 'w') >>> cPickle.dump(obj, File) >>> File.close() >>> >>> file1=open('test', 'r') >>> objct=cPickle.load(file1) >>> file1.close() >>> objct.A Traceback (most recent call last): File "<pyshell#55>", line 1, in -toplevel- objct.A AttributeError: A >>> objct.C 1 Its own attribute (C) value is restored but the value of an inherited attribute (A) is not. I tried pickling protocol 2, and module pickle instead of cPickle, all with the same result. What can be done?! Or maybe nothing can be done? I would greatly appreciate an advice. A lot of code is written, but now we have a need for pickling and unpickling objects and discovered this problem.

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Re: Scanning a file
by Paul Watson Oct. 31, 2005

Oct. 31, 2005

Fredrik Lundh wrote: > Paul Watson wrote: > >>This is Cyngwin on Windows XP. > > using cygwin to analyze performance characteristics of portable API:s > is a really lousy idea. Ok. So, I agree. That is just what I had at hand. Here are some other numbers to which due diligence has also not been applied. Source code is at the bottom for both file and mmap process. I would be willing for someone to tell me what I could improve. $ python -V Python 2.4.1 $ uname -a Linux ruth 2.6.13-1.1532_FC4 #1 Thu Oct 20 01:30:08 EDT 2005 i686 $ cat /proc/meminfo|head -2 MemTotal: 514232 kB MemFree: 47080 kB $ time ./scanfile.py 16384 real 0m0.06s user 0m0.03s sys 0m0.01s $ time ./scanfilemmap.py 16384 real 0m0.10s user 0m0.06s sys 0m0.00s Using a ~ 250 MB file, not even half of physical memory. $ time ./scanfile.py 16777216 real 0m11.19s user 0m10.98s sys 0m0.17s $ time ./scanfilemmap.py 16777216 real 0m55.09s user 0m43.12s sys 0m11.92s ============================== $ cat scanfile.py #!/usr/bin/env python import sys fn = 't.dat' ss = '\x00\x00\x01\x00' ss = 'time' be = len(ss) - 1 # length of overlap to check blocksize = 64 * 1024 # need to ensure that blocksize > overlap fp = open(fn, 'rb') b = fp.read(blocksize) count = 0 while len(b) > be: count += b.count(ss) b = b[-be:] + fp.read(blocksize) fp.close() print count sys.exit(0) =================================== $ cat scanfilemmap.py #!/usr/bin/env python import sys import os import mmap fn = 't.dat' ss = '\x00\x00\x01\x00' ss='time' fp = open(fn, 'rb') b = mmap.mmap(fp.fileno(), os.stat(fp.name).st_size, access=mmap.ACCESS_READ) count = 0 foundpoint = b.find(ss, 0) while foundpoint != -1 and (foundpoint + 1) < b.size(): #print foundpoint count = count + 1 foundpoint = b.find(ss, foundpoint + 1) b.close() print count fp.close() sys.exit(0)

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Re: Scanning a file
by netvaibhav＠gmail.com Oct. 31, 2005

Oct. 31, 2005

Steve Holden wrote: > Indeed, but reading one byte at a time is about the slowest way to > process a file, in Python or any other language, because it fails to > amortize the overhead cost of function calls over many characters. > > Buffering wasn't invented because early programmers had nothing better > to occupy their minds, remember :-) Buffer, and then read one byte at a time from the buffer. Vaibhav

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Controlling output using print with format string
by Paul Watson Oct. 31, 2005

Oct. 31, 2005

It is clear that just using 'print' with variable names is relatively uncontrollable. However, I thought that using a format string would reign the problem in and give the desired output. Must I resort to sys.stdout.write() to control output? $ python Python 2.4.1 (#1, Jul 19 2005, 14:16:43) [GCC 4.0.0 20050519 (Red Hat 4.0.0-8)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> s = 'now is the time' >>> for c in s: ... print c, ... n o w i s t h e t i m e >>> for c in s: ... print "%c" % (c), ... n o w i s t h e t i m e >>> for c in s: ... print "%1c" % (c), ... n o w i s t h e t i m e

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