🌐 Mailman 3 September 2003 - Tutor - python.org

Backslashes inside of variable
by Phoebus Nov. 24, 2003

Nov. 24, 2003

I am running Python 2.2 on Win2k. I have a program which writes a filename, with backslashes to a file, along with other stuff. I read the file in using readlines() and put each line into a variable. My problem is I want to use the filename, but I can't use it because of the backslashes. I know about doing open(r"d:\test\file.txt","w") or even open(`d:\test\file.txt`,"w"), but the filename is inside of a variable so when I do open(filename,'w'), I have problems. Can anyone help? Thanks, Steve --

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Introduction and ? re: searching the list's archives
by Robert Lilly Oct. 24, 2003

Oct. 24, 2003

Hello everyone, My name is Robert and I just signed up to the list. I am looking forward to learning how to program using Python. My background in programming is limited to Visual Basic, which some would say means I don't know anything about programming. ;-) I have written several sophisticated programs using MS Excel and VB, including a real-time signaling program for stock trading. I am not familiar with programming that isn't tied into some other application's object model, however. So, for all intents and purposes, I am learning both the Python programming language and object-oriented programming. I know that many of the questions I will want to ask have probably already been discussed. So I've downloaded the mbox archive so that I may search through it before asking a question. However, I'm not sure what an efficient means for searching it may be. Does anyone have any recommendations on how to go about searching an mbox archive? I am working primarily under Windows 2000, but I have Cygwin installed, so a *nix solution may be viable as well. I'm not sure what the etiquette for this group is yet, so forgive me if this post is off-topic. Thanks, Robert Lilly

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re-directing print statements in exec
by Toby Donaldson Oct. 10, 2003

Oct. 10, 2003

Hi all, I am wondering if there is any easy way to make a print statement in an exec statement get sent to a string instead of the console. For instance, >>> prog = """ r = 5 print 3.14 * r ** 2 """ >>> exec prog 78.5 The result gets printed to the console. But instead, I'd like it to be in a string. Any suggestions? Toby

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I need help with Python
by Vickram Oct. 10, 2003

Oct. 10, 2003

Hello there, Python is really an excellent programming language, in terms of mathematical calculations. I have had a first hand experience of the power of python while using the Mayalib source code for python to calculate mayan dates. However, i am currently experiencing some problems in writing my own program as i am not a language programmer. I need to make calculations using very large numbers, unfortunately, i am getting a "ZeroDivisionError: float division" error. Can you please help me out? What follows is my program. Its simple and brief, yet it is actually calculating one of the best proven theories in science - special relativity. import cmath a = 186282.397 b = 1609.344 c = 365.2421987817 d = 99.9999999999999999995 e = (d*a)/100 beta = ((e*b)**2) / ((a*b)**2) gamma = 1/math.sqrt(1-beta) ty = 100000 td = ty*c print print "speed of light =",a,"mps" print "1 mile =",b,"metres" print "1 year =",c,"days" print print "% of c =",d,"%" print "gamma =",gamma print print "normal time = ",ty,"years" print " ",td,"days" print print "time dilation =",ty/round(gamma),"yrs" print " ",td/gamma,"days" Thanking you Vickram

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Limit on number of characters in a string?
by Jeffery Chin Oct. 10, 2003

Oct. 10, 2003

Is there a limit on how many characters can be in a string? I'm using pythonwin with python 2.3 and there seems to be a limit. I'm trying to concatenate lines from a file to make one continuous string and it won't grow beyond a certain length. I think it cuts it off around 3800 characters, but this was not consistent, but looking at the screen output, it certainly would not add more to the string. script would read in the file and check whether to concatenate the line to the string: elif (record_check == ','): interim_list.append(logline_path + entry + '.txt;') looking at the screen output and what is written to a file, it will not continue to write to the string after it hits a certain length. If there isn't such a limit there must be an error elsewhere, but it seems to work fine for the shorter strings. Jeffery

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translating some python code to perl
by Lloyd Kvam Oct. 6, 2003

Oct. 6, 2003

I need to provide the contents of a python dictionary to a perl programmer as a perl hash table. However, the python dictionary contains dictionaries, and I have been unable to figure out the perl syntax for nexting and referencing hash tables. Here's a python sample: #python d1 = {'1': 'one', '2': 'two', 'd2': {'nest1': 'nest one', 'nest2': 'nest two',} } d1['1'] # returns 'one' d1['d2'] # returns the d2 hash d1['d2']['nest1'] # returns 'nest one' Here is my attempted perl equivalent: #!/usr/bin/perl # testhash.pl %d1 = ( '1' => 'one', '2' => 'two', %d2 = ('nest1' => 'nest one', 'nest2' => 'nest two',) ); print "\nlookup 1 in d1: $d1{'1'}\n"; print "\nlookup d2 within d1: %d1{'d2'}\n"; print "\nlookup nest1 in d2 within d1: $d1{d2}{'nest1'}\n"; ###end of perl script $d1{'1'} returns the scalar 'one' So that's as far as I was able to go. I am not sure if my hash table is correct. Please help me fix the hash table definition and the references so that I can verify that it works. -- Lloyd Kvam Venix Corp. 1 Court Street, Suite 378 Lebanon, NH 03766-1358 voice: 603-443-6155 fax: 801-459-9582

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Classes and the like...
by Intatia Oct. 5, 2003

Oct. 5, 2003

Hey, new to the list and have a little question.. Does anyone know of a good link that explains classes and what's associated with them in realllly simple terms, because my friend has managed to totally confuse me. A little bit on what they are and how to use them and why they do what they do. Thanks.

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Project Parallelport
by Vadim Usenko Oct. 4, 2003

Oct. 4, 2003

Hi all, I am searching for a module in python to connect a programm directly with the parallel port to build a mini-crossway with some traffic lights. Do you have some information for me, please? Thanks, Vadim

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mailing list archive reader
by roy ollis Oct. 1, 2003

Oct. 1, 2003

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Complaint about maximum recursion
by Jonathan Hayward http://JonathansCorner.com Oct. 1, 2003

Oct. 1, 2003

My script now gets this error on starting up. What is wrong if a 50-line stack trace complains about excessive recursion? Traceback (most recent call last): File "/home/jonathan/creations/software/inventions/datamine/fathersd", line 3878, in ? multitasking.start_oracle() File "/home/jonathan/creations/software/inventions/datamine/fathersd", line 2288, in start_oracle server_init() File "/home/jonathan/creations/software/inventions/datamine/fathersd", line 3802, in server_init section.get_documents(1) File "/home/jonathan/creations/software/inventions/datamine/fathersd", line 2614, in get_documents self.possibly_include_files_from_directory, "") File "/usr/lib/python2.2/posixpath.py", line 287, in walk walk(name, func, arg) File "/usr/lib/python2.2/posixpath.py", line 279, in walk func(arg, top, names) File "/home/jonathan/creations/software/inventions/datamine/fathersd", line 2681, in possibly_include_files_from_directory self) File "/home/jonathan/creations/software/inventions/datamine/fathersd", line 857, in get_document return webpage(filename, section) File "/home/jonathan/creations/software/inventions/datamine/fathersd", line 2805, in __init__ document.__init__(self, filename, section) File "/home/jonathan/creations/software/inventions/datamine/fathersd", line 637, in __init__ self.process() File "/home/jonathan/creations/software/inventions/datamine/fathersd", line 808, in process self.compute_title() File "/home/jonathan/creations/software/inventions/datamine/fathersd", line 2948, in compute_title self.title = self.get_tag_contents("title", self.get_file_contents()) File "/home/jonathan/creations/software/inventions/datamine/fathersd", line 763, in get_tag_contents internal = self.get_tag_contents_internal(tag, file_contents) File "/home/jonathan/creations/software/inventions/datamine/fathersd", line 772, in get_tag_contents_internal return my_re.findall(file_contents) RuntimeError: maximum recursion limit exceeded TIA, -- ++ Jonathan Hayward, jonathan.hayward(a)pobox.com ** To see an award-winning website with stories, essays, artwork, ** games, and a four-dimensional maze, why not visit my home page? ** All of this is waiting for you at http://JonathansCorner.com

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