🌐 Mailman 3 February 2013 - Tutor - python.org

Wave module
by Alex Krycek Feb. 12, 2015

Feb. 12, 2015

Hello, I'm trying to join two .wav files with the wave module. But when I try to use wave.open(filename, "rb") I receive the following error: Traceback (most recent call last): File "<stdin>", line 1, in <module> File "F:\PortablePython1.0\lib\wave.py", line 483, in open return Wave_read(f) File "F:\PortablePython1.0\lib\wave.py", line 162, in __init__ self.initfp(f) File "F:\PortablePython1.0\lib\wave.py", line 143, in initfp self._read_fmt_chunk(chunk) File "F:\PortablePython1.0\lib\wave.py", line 264, in _read_fmt_chunk raise Error, 'unknown format: %r' % (wFormatTag,) wave.Error: unknown format: 85 I read somewhere that there are various wave formats, only some supported by Python. Is this true? If so, is there any way I can convert my wave files into a supported kind? Thanks!

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getUncPath(mappedDrive)
by Albert-Jan Roskam Jan. 31, 2014

Jan. 31, 2014

Hi, Is there a function that takes a file path with a mapped drive (z:\blah) and returns the associated UNC path (\\server\share\ding\dang\dong\blah)? I looked in os.path, but it doesn't seem to have this. The link below seems to be a solution (code in the bottom of the page), but I can't install win32com.client in the office :-( Is there any built-in function? http://stackoverflow.com/questions/2244767/python-check-network-map Thanks! Regards, Albert-Jan ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ All right, but apart from the sanitation, the medicine, education, wine, public order, irrigation, roads, a fresh water system, and public health, what have the Romans ever done for us? ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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How to unpack python-dateutil-2.0.tar.gz
by Richard D. Moores Sept. 5, 2013

Sept. 5, 2013

Python 3.2.3 64 bit MS Windows 7 Home Premium 64-bit SP1 I see python-dateutil recommended here from time to time, so I thought I'd try it out. I downloaded python-dateutil-2.1.tar.gz from http://pypi.python.org/pypi/python-dateutil but have forgotten how to unpack a .tar.gz file. Please remind me. Thanks, Dick Moores

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using ranges with argparse()
by Kurt Lieber July 20, 2013

July 20, 2013

Hi -- brand new to python, but trying to write a simple script that takes command line arguments. One of the arguments needs to test if a value is a) an integer and b) within a stated range. I currently have: parser.add_argument("-f", "--floor", default=6000, help="floor is the minimum amount of bonus points.",type=int, choices=range(5995, 6001)) This works, but when the user enters an out of bounds value, the help message is unfriendly: % ./bonus.py -f 10000 usage: bonus.py [-h] [-f {5995,5996,5997,5998,5999,6000}] MAM-bonus.py: error: argument -f/--floor: invalid choice: 10000 (choose from 5995, 5996, 5997, 5998, 5999, 6000) The problem is my default range is actually 0,10000 -- I changed it above for brevity's sake. So in the real world, it floods the screen to the point where it's unreadable. I can suppress the whole thing with argparse.SUPPRESS, but then I'm left with no help message at all. Is there a way to suppress the "(choose from 1,2,3,etc.)" part of the help message? Or a cleaner/different way altogether to accomplish the same thing? thanks.

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Set Reply-To field to Tutor@python.org
by Oscar Benjamin April 10, 2013

April 10, 2013

I have both sent and received messages on this list that went off-list by mistake. It's an easy mistake to make that you use reply instead of reply-all and then the message goes just to one person instead of the whole list. This problem is not unique to the python-tutor. I see it happening often on other mailing lists (often it's noticeable by the fact that someone forwards an off-list message back to the list which can sometimes break the threading of email software). One particular list that I receive has recently made an administrative change so that, from now on, all emails have the "Reply-To" header set to the list address. This means that the default behaviour when replying to a message is that the reply goes to the list. I think that this is the right thing to do by default since replying off-list is much less common and more likely to be something that you are consciously aware of when you do it. The change seems to have gone down well on the other list so I wondered: could it be done for this list as well? Oscar

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timeit: 10million x 1 Vs 1million x 10
by DoanVietTrungAtGmail Feb. 28, 2013

Feb. 28, 2013

Dear tutors My function below simply populates a large dict. When measured by timeit populating 10 million items once, versus populating 1 million items ten times, the times are noticeably different: --- import timeit N = 10000000 # This constant's value is either 10 million or 1 million testDict = {} def writeDict(N): for i in xrange(N): testDict[i] = [i, [i + 1, i + 2], i + 3] print timeit.Timer('f(N)', 'from __main__ import N, writeDict as f').timeit(1) # the 'number' parameter is either 1 or 10 --- Result from 3 runs of 10 million x 1 time: 12.7655465891, 13.1248426525, 12.1611512459 Result from 3 runs of 1 million x 10 times: 14.3727692498, 14.3825673988, 14.4390314636 I ran Python 2.7 on Pycharm on Windows 7. My guess is that this discrepancy is a result of either how some sort of overhead in timeit, or of Python having to allocate memory space for a dict 10 times. What do you think, and how to find out for sure? Second (for me, this question is more important), how to improve performance? (I tried a tuple rather than a list for the dict values, it was slightly faster, but I need dict items to be mutable) Thanks Trung Doan

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There's a Programmer in Me
by Khalid Al-Ghamdi Feb. 27, 2013

Feb. 27, 2013

Hi All, I'm not a programmer by profession, but I want to learn python. I've got lots of Ideas that want to realize, but I always run into these stupid hiccups where I follow the tutorials and something stupid (known/unkown) is causing things not to work ... frustration ensues... After more than 2 years (on and off) I've got the basics down and have written some scripts, but I want some place online where a live person can tutor me to the next level. Any good suggestions? As always, many thanks for your great advice.

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Second follow up
by Jack Little Feb. 26, 2013

Feb. 26, 2013

How would I go from one def statement to another? I am developing a text based rpg. Sent from my iPod

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object attribute validation
by neubyr Feb. 25, 2013

Feb. 25, 2013

I would like to validate data attributes before the object is instantiated or any changes thereafter. For example, following is a simple Person class with name and age attributes. I would like to validate whether age is an integer before it is added/changed in the object's dictionary. I have taken a simple integer validation example, but it could be something like DateField validation or X509 certificate validation as well. Following is my example code: class Person(object): def __init__(self,name,age): self.name = name self.age = age def get_age(self): return self._age def set_age(self,val): try: int(val) self._age = val except ValueError: raise Exception('Invalid value for age') def del_age(self): del self._age age = property(get_age,set_age,del_age) a = Person('John',6) b = Person('Johny','Six') Is this a good approach? Any suggestions for improving the code or alternative approaches would be helpful. -- thanks, neubyr

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How to change the char in string for Python
by Sudo Nohup Feb. 24, 2013

Feb. 24, 2013

Dear all, I want to change the value of a char in a string for Python. However, It seems that "=" does not work. Could you help me? Thanks! str = "abcd" result = [char = 'a' for char in str if char == 'c'] OR: str = 'abcd' for char in str: if char == 'a': char = 'c' OR: str = 'abcd' for i in range(len(str)): if str[i] == 'a': str[i] = 'c' ( Traceback (most recent call last): File "<stdin>", line 3, in <module> TypeError: 'str' object does not support item assignment ) James

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