🌐 Mailman 3 July 2005 - Tutor - python.org

Postgresql+Python -tutorial?
by Olli Rajala Feb. 11, 2006

Feb. 11, 2006

Hi! I've been using MySQL up this day, but would like to convert my program to use Postgresql. There seems to be awful lots of tutorials for MySQL+Python, but not so many for Postgresql+Python. Where should I start? I'm not very good at database things, but have written some little programs with MySQL+Python/Php/Java. So, if you have some good tutorials or something else info, I'd be glad to know! Oh, I can install additional modules, but it would be great if Ubuntu had them... Thanks! -- Olli Rajala <>< Tampere, Finland http://www.students.tut.fi/~rajala37/ "In theory, Theory and Practice should be the same. But in practice, they aren't." - Murphy's Proverbs

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What does Python gain by having immutable types?
by Tony C Nov. 15, 2005

Nov. 15, 2005

A friend recently asked my this didn't modify his original string variable s1="this is a string" s1.replace("is a", "is a short") "this is a short string" print s1 "this is a string" After showing him to change it to this s1 = s1.replace("is a", "is a short") print s1 "this is a short string" He then asked Why is it that the sort operation modfies the original list variable? l1=[] l1.append(3) l1.append(44) l1.append(1) l1.append(22) l1 [3, 44, 1, 22] l1.sort() l1 [1, 3, 22, 44] I don't know, but I think it has something to do with strings being immutable, whiles lists are mutable. So, other than the non-informative answer " because that's how the language was written" are there any other reasons how Python benefits from immutable types? Does it really matter if s1 is a different object, so long as it contains the expected modified string? The list variable is the same object, and contains the sorted list, so why bother with the complexity of immutable types at all?

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Program to lock folders under win32
by Mark Kels Sept. 4, 2005

Sept. 4, 2005

Hi list. I want to make a program to lock folders (so the user can only access them if he knows the password) under win32, the only problem is that I have no idea how to start or what to do. Do you guys have any ideas of how to do it? Thanks! -- 1. The day Microsoft makes something that doesn't suck is probably the day they start making vacuum cleaners. 2. Unix is user friendly - it's just picky about it's friends. 3. Documentation is like sex: when it is good, it is very, very good. And when it is bad, it is better than nothing. - Dick Brandon

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IDLE not working?
by Jeff Peery Aug. 5, 2005

Aug. 5, 2005

Hello, I upgraded python to 2.4 and now my IDLE isn't working. There is an error indicating something is wrong with my configuration file for the IDLE settings. Any suggestions for how to solve this problem would be much appreciated. thanks. Jeff

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Help with file I/O.
by Nathan Pinno Aug. 4, 2005

Aug. 4, 2005

If anyone will help me learn file I/O, it would be appreciated. I went through Josh Cogliani's Non-Programmer's Tutorial for Python, and I still can't understand it. Thanks in advance, Nathan Pinno

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How do I add an argument too...
by Joseph Quigley Aug. 3, 2005

Aug. 3, 2005

How do I add an argument too my program (with sys.argv) so that at a console I can type: python foo.py -info or python foo.py open /home/joe/foo.txt Thanks, Joe

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try except continue
by tpc＠csua.berkeley.edu Aug. 1, 2005

Aug. 1, 2005

hey guys, so I've been trying to get my head around the try except statement in Python, and ideally what I'd like is for my procedural program, when it runs through its steps and encounters an error, to log the error and pick up where it left off and keep going. According to this link, 'continue' is allowed within an except or finally: http://python.active-venture.com/ref/continue.html I tried to run the following code, expecting to catch a NameError and continuing on: def someFunc00(): someModulo = 6%2 print someModulus def someFunc01(): print "yeah!" def someFunc02(): print "baby let's go" def someFunc03(): someInt = 2+2 print "someInt is: ", someInt def someProcedure(): someFunc00() someFunc01() someFunc02() someFunc03() # copy and paste the following into IDLE, which on my machine often #crashes for an unknown reason, so I've taken to creating a harness that #imports the required library and then runs the desired programs to test #the desired behavior if __name__ == "__main__": import testTryCatch try: testTryCatch.someProcedure() except: print "encountered error" continue but I get the following error: SyntaxError: 'continue' not properly in loop What am I doing wrong ?

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fourier transform
by Jeff Peery Aug. 1, 2005

Aug. 1, 2005

Hello, I have a signal that I want to do a fourier transform on. I tried using FFT.fft(data).real but I don't understand the output. what is output from this function, and why doesn't it require amplitude and time as inputs? thanks.

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Re: [Tutor] fourier transform
by Christian Meesters Aug. 1, 2005

Aug. 1, 2005

Jeff Peery wrote: > > Hello, I have a signal that I want to do a fourier transform on. I > tried using FFT.fft(data).real but I don't understand the output. > what is output from this function, and why doesn't it require > amplitude and time as inputs? Hi Jeff, As Danny wrote, your input are real numbers and your output will be complex numbers. I don't want to point you to the numarray documentation once more, but you might to check out this: http://mathworld.wolfram.com/FourierSeries.html as for why you get complex numbers back. (To get only the real value part try real_fft() in numarrayl.) In general in numerical computation your input is simply a series of real numbers - of equal spacing in the dimension you want to consider. Which dimension you choose (amplitudes and time/phase or amplitudes and spacial frequencies and so on) is up to you. It depends on your physical or mathematical question. IMHO the best introduction you can get on Fourier Transforms & programming can be found in Numerical Recipies (here the "Numerical Recipies in C"-link http://www.library.cornell.edu/nr/bookcpdf.html - check chapter 12). Have fun with FFTs! Cheers Christian

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Performance difference, ``in'' vs ``has_key()''
by Bill Campbell Aug. 1, 2005

Aug. 1, 2005

I'm going to be doing some work where I'll be doing existence testings on keys on about a million records where it may require multiple passes so I'm a bit concerned about the timing of these tests. Is there any significant performance difference between the tests, ``key in dictionary'' and ``dictionary.has_key(key)''? I would prefer using the ``key in'' because it's a bit easier to type, and can also be used with lists in addition to dictionaries. A related question is where's the trade-off between using ``in'' with a list, and a dictionary? I presume that using it with small hashes will be faster than dictionries since it doesn't have to calculate the hashes. Bill -- INTERNET: bill(a)Celestial.COM Bill Campbell; Celestial Software LLC UUCP: camco!bill PO Box 820; 6641 E. Mercer Way FAX: (206) 232-9186 Mercer Island, WA 98040-0820; (206) 236-1676 URL: http://www.celestial.com/ Government is the great fiction, through which everbody endeavors to live at the expense of everybody else. -- Frederic Bastiat

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