🌐 Mailman 3 June 2002 - Tutor - python.org

Backslashes inside of variable
by Phoebus Nov. 23, 2003

Nov. 23, 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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Re: [Tutor] changes in Python 2.2
by Alexandre Ratti July 15, 2002

July 15, 2002

At 04:26 26/06/2002 -0400, tutor-request(a)python.org wrote: >From: "Scot W. Stevenson" <scot(a)possum.in-berlin.de> >Subject: Re: [Tutor] changes in Python 2.2 >Date: Wed, 26 Jun 2002 10:22:30 +0200 [rate of changes in Python] >I remember complaining a few months ago about Python's rate of >change, and tho I have made lots of progress with the language since then >(with a lot of help from this list), switching to 2.2 does make me feel >like the road I was following has dwindled from a four-lane highway (or >rather /Autobahn/ in my case) to a packed-earth path thru the forest. I am >not sure if the real computer people here realize how disorientating these >changes are for people who are struggling with the basic concepts. Well, obviously in Python we have a tension between being a learner's language and an "advanced" language for experienced programmers. So far, I believe the designers have found an acceptable balance, though I admit there were a lot of changes in the last months. >List comprehensions are, as we have discussed here before, very intuitive >if you have a background in set theory (so I'm told), but for the rest of >us, they are not exactly easy on the eyes, and I still think the syntax >looks very un-Pythonic. They are not exactly the simplicity that Python >has been famous for, and certainly not "executable pseudocode". Frankly, there are all kind of people here. I don't have any formal background in computer science, let alone set theory (the first language I messed with was called WordBasic - believe me, you don't want to use it). However, list comprehensions somehow fit my brain. I use them all the time; they feel natural, whereas I have a hard time with lambda, reduce, recursive stuff, etc. >division is about as basic as you can get, and at this rate of change, >we're going to hit Python 3.0 before anybody gets around to writing those >new books. Take a look at how many division examples that is going to >break - starting on page 33 of "Learning Python", which is about as close >to the start of learning the language as you can get. This is doing to >really get the next generation of newbies. >Again, I am not opposed to the changes as such. Having "real" division >instead of C-like computer science division is a great idea and in my mind >will be a great plus for Python. Yes, a lot of people were worried about this change. I also believe it is a improvement, because integer division is not very intuitive for new learners. >The problem is that the rate of change has far outstripped the ability (or >interest) of the people writing documentation to keep up, especially >documentation in book form. However, I think many news Python books were published in the last months. This is a positive trend for Python. I feel there is a growing interest in the language. >For the rest of us, learning Python 2.2 means piecing together bits from >outdated books (like "Programming Python"), short online texts (like >"What's new in Python 2.2.?", which, as Thomas pointed out, is not aimed >at newbies), and comments from more advanced users (like the Python Tutor >list here). You may have a point here. Maybe we need a tutorial for new features, eg. a new leaners' guide to new features. Anyone? >As much as I have gotten to love Python, I am beginning to ask myself why >I don't just quit the language for a while until the mutation rate has >dropped to an acceptable level. I'm not sure how you use Python (eg. do you use it in your job, etc.) I use it both for fun and to automate tasks in my work (but I'm not a programmer). The new Python features do not prevent me from using Python (actually, I'm still using 2.1 a lot). Also, I don't feel I have to learn new features immediately. Usually, I can wait until they are better understood and better documented (or until I really need them and I have an incentive for learning them). > Y, Scot >Who does feel a lot better now, thank you... :-) Cheers. Alexandre

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addition
by Terje Johan Abrahamsen July 5, 2002

July 5, 2002

Hello, I have to make a program that compares policies for an accounting department. It uses two different systems, AS/400 and Win Excel. I have built all the surounding code moving numbers back and forth, formatting and so forth, but the main calculations are missing. Here is the problem: In Excel up to 7 accounts can have the same policynumber, while up to 3 policies in the AS/400 system can have the same policynumber. Any number of policies in either system can match any number of policies in the other system. So, therefore for example 5 Excel amounts can add up to the approximate amount (+-$5) of 2 AS/400 accounts. If this is the case, these amounts should be marked. If I haven't forgotten all my statistics skills, that should equal up to (7!=5040 * 3!=6)=30240 calculations. How can I do this? There is no way I can use my normal way of doing this (with less numbers) by writing in the possibilities, as in if a+b=c:print yes, elif a+c = d: print yes and so forth until I have used all the possibilities. I need the computer to do this part this time. (I am a beginner, so please keep it simple.) Thanks, Terje _________________________________________________________________ Join the worlds largest e-mail service with MSN Hotmail. http://www.hotmail.com

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installing/starting vPython
by val July 3, 2002

July 3, 2002

Hi The List, i downloaded and installed vPython for Python22. i'm trying to run demos from the Demos dir by double- clicking on *.py files. It works impressively fine on my job (same win2k, both Py21 and Py22 are installed). At home i have a standard message from vPython and then just an empty window (or two or three depending on the demo to be run). Any help/advice would be very appreciated. thanx, val

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game help
by David & Sheri Early July 1, 2002

July 1, 2002

hello my name is chris and am trying to use python to start creating a game but everywhere i look for resources i come up at a dead end. help! ~Chris~

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Re: [Tutor] drag-and-drop argument passing
by Pijus Virketis July 1, 2002

July 1, 2002

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Progress Bar Help.
by Scott Comboni July 1, 2002

July 1, 2002

I recently wrote a simple python script to install a bunch of software apps and would like to jazz it up with some sort of graphical progress bar. Is there some URL someone can point me too to get some ideas on how to code/create something like this? Thanks All. Scott -- ____________________________________________________________

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RE: [Tutor] Re: pair programming.
by alan.gauld＠bt.com June 30, 2002

June 30, 2002

> The biggest problem with modality in vi*'s is that you may be in > command mode but think you're in insert and type some stuff which > will garble your text in a scary random-looking manner. > I myself never found this to be much of a problem, but I know some > people do.. Those folks obviously never used Tico... ;-) The standard programmers game in Tico was to type your name and try to guess what the effect would be on your code(*)! The only good thing I can say about Tico is that it was so bad it drove James Gosling to invent the original Emacs! Alan G. (*)Actually on your computer since it was entirely possible to accidentally delete files, format disks etc by typing seemingly inoccuous character strings into Ticos command line interface... PS Anyone on a Vax running VMS can still experience Tico by typing EDIT/TICO at a DCL prompt - Good luck!!

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RE: [Tutor] Matrix class problems
by alan.gauld＠bt.com June 30, 2002

June 30, 2002

> Firstly, I would like to know what exactly repr() does. I read the > docs, and this is what I got : > ... > Return the canonical string representation of the object. > For most object types, eval(repr(object)) == object. > """ > > What does this mean and how is this different from str() ? repr is a pythonic representation of an object as a string. str is a human readable version. You can see the difference at the prompt by typing values with and without the print command: >>> print 5 # uses str() 5 >>> 5 # uses repr() 5 >>> # the above are identical >>> s = "Hello world" >>> print s Hello world >>> s "Hello world" >>> # notice repr added qutes whereas str didn't Coming back to the doc string comment consider what happens with eval: eval(Hello world) # error, looks for variables called hello & world eval ("Hello world") # works. It gives us a string back Hope that makes the diffrence a bt clearer Alan g. Author of the 'Learning to Program' web site http://www.freenetpages.co.uk/hp/alan.gauld

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RE: [Tutor] help on makin a prog
by alan.gauld＠bt.com June 30, 2002

June 30, 2002

> Hey im really really new to this stuff and i would like some > help so could > any1 try teach me? i know a few things raw_input("Hello, world") and > print"hello world so cud u teach me how to make a proper program? Go to the Beginners page on the python web site and work through one of the tutorials there. Everytime you hit something yuou don't understand send the question to this list. A whole bunch of folks will then spring into action trying to answer it. Try to be as specific as possible and if you get error messages include them in the mail. Thats how the list works, have fun. Alan g. Author of the 'Learning to Program' web site http://www.freenetpages.co.uk/hp/alan.gauld

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