🌐 Mailman 3 August 2000 - Python-list - python.org

Python in game development?
by Mallor Sept. 28, 2000

Sept. 28, 2000

Are any of you game developers out there using Python as your game engine's embedded scripting language? I am wondering what drove your decision to use Python instead of other embeddable scripting languages? I'd like to hear what your overriding concerns were, and also what they are now, having put Python to the test. -- Cheers, Infernal Troublemaker Troll Mallor "By simple mistake, mortals themselves amuse."

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Python advocacy for device testing?
by redhouse＠my-deja.com Sept. 27, 2000

Sept. 27, 2000

So I am a python newbie. I have done a week or two of working through exercises and read most of "Learning Python." I am trying to sell it as a testing infrastructure language in my test automation group. Does anybody have any experience in this arena? The goal is to create a testing infrastructure for an optical networking product. The prime competition is TCL, of which I am not a big fan. Has anybody out there used python in this sort of application? Have you used it to interface with network testing equipment to do things like load testing and impairment? Thanks- Carter Sent via Deja.com http://www.deja.com/ Before you buy.

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gif to bitmap in python
by tiddlerdeja＠my-deja.com Sept. 27, 2000

Sept. 27, 2000

Can anyone tell me how, or give an example of howto convert a gif image to a bitmap representation of it? I'll be loading the image from a URL. Any information appreciated. Sent via Deja.com http://www.deja.com/ Before you buy.

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Re: deltree function
by François Pinard Sept. 22, 2000

Sept. 22, 2000

[Arkaitz] > Is there a deltree-like function in the Python standard library? I have > been looking at os.removedirs(), but it won't delete non-empty > directories. I'd like to delete a whole tree, with files and directories > mixed, as rm -rf does in Unix. Any hint? Hello, Arkaitz. As others suggested, the simplest is to execute the shell command `rm -rf' from within your Python program. However, if I wanted a pure Python solution, I would slightly modify a script I wrote to clean out a file hierarchy from the empty directories it contains, which script is attached to this message. The modification, untested, would be to add a loop at the beginning of the `walker' script, so it starts like this: def walker(dummy, directory, bases): for base in bases[:]: name = os.path.join(directory, base) if os.path.isfile(name) or os.path.islink(name): os.remove(name) bases.remove(base) while not bases: # etc. Maybe that some code would also be needed to handle the cases where permissions are not sufficient to remove files or directories. -- François Pinard http://www.iro.umontreal.ca/~pinard

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deltree function
by Arkaitz Sept. 22, 2000

Sept. 22, 2000

Hi All, Is there a deltree-like function in the Python standard library? I have been looking at os.removedirs(), but it won't delete non-empty directories. I'd like to delete a whole tree, with files and directories mixed, as rm -rf does in Unix. Any hint? Thanks in advance, Arkaitz

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Stdin problems in cgi
by Sindh Sept. 21, 2000

Sept. 21, 2000

Hi folks I am using oython for my cgi dev. I wrote a page with a few file upload buttons. When I try to submit files , the cgi script reads the files ok as long as they are not binary. If they are binary it waits for ever. Somewhere, on thin news group I read that I have to change stdin to bainary mode but the python documentation does not give any clues. So how do yuo set stdin to binary. Your help would be appreciated. Thanks sreekant -- A man needs to sleep for 36 hours a day atleast. Sent via Deja.com http://www.deja.com/ Before you buy.

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Python 1.6 The balanced language
by thor＠localhost.localdomain Sept. 21, 2000

Sept. 21, 2000

Python 1.6 The balanced language (I'd say 1.5.2, but...) --------------------------------- Python has many features from many languages: * Functional features: - Lambda, filter, map, eval. And for i in list: constructs . I've heard some occaml fans say: "I like python because of these features" * OO features: - Classes, objects. * Simple programming features: - print statement, simple assignments, lists and tuples, asserts, docstrings and comments, import mechanism, "input"... (some others), open file... * A small but big enough set of functions : max, min, range, pow, string.join, re.match ... And that's python, no more and no less. And that's the greatness of python. Of course, we could add in: * Functional features: - Patterns for lists: l [ head : lists] * OO features: - Design by contract - Strong "typing" * Simple programming features: - Corroutines - A bigger set of operators ( << ...) - Lexical closures ... The question is that the current balance of "powers" inside python prevents people of any of the families from writing python ununderstable for the rest of the families. So, functional-guys, although may do a lot of _harm_ in dark lambda-map expressions, they can't add to _their_ expression-confussion those "awful" patterns. So, Java-C++-guys, although they can write 200 lines-long-functions (a la Java ), they can't do too much harm because they can't use their most fearful weapon : hard typing. So , their code is still understable. So, academic-researchers-learners, although they can do of dict-tricky constructs, they can't do nasty corroutines, lexical scopes (a la Scheme), which would be ununderstable for the C++ guys. So, as you see, Python is more a balance of forces than anything else. What will happen in Python 3000 ? Well, that balance will be broken and python won't make sense any more. Sure, it'll be the same language : python. But, people will experience __always__ some kind unrest, because advanced features of some of the families will pop up, and nobody belongs to all the families. So Java-C++ guys will have hard times with functional, Functional-guys will have hard times with hard types... The current state of forces is an achievement. And the work to do should enroute into: - (Still) Better documentation. Better systems of organizing examples (snippets) but seriously. - Provide clear ways (with clear doc) to expand the language for any of the families or for some programs : Oracle, mails - Sort all the apps available and try to organize them as example for reusing the code. I've hear a Macintosh user say this: " I consider still TCL the language of choice, but python fits so well in the Mac,... I can write GUI's and call Mac primitives,... everything is so smooth". Well, let's continue that path, and let's do betterment in the library/app/documentation layer, instead of Python itself. Thinking that python can be : Eiffel + Haskell + Java is simply ___DUMB___ and irrealistic. Sometimes there are even technical drawbacks: if you use Stackless python (corrutines), you can use Jpython compatibility ! --- MGA

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Why don't I get a .pyc file?
by rickp＠telocity.com Sept. 19, 2000

Sept. 19, 2000

I'm running linux, python 1.5.2. Isn't a .pyc file supposed to be automatically created whenever I run a .py file? Why don't I get one for the program I wrote? -- "It is often easier for our children to obtain a gun than it is to find a good school." -- Joycelyn Elders "Maybe that's because guns are sold at a profit, while schools are provided by the government." -- David Boaz Rick Pasotto email: rickp(a)vnet.net

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Re: reducing fractions
by Kirby Urner Sept. 15, 2000

Sept. 15, 2000

"Janet Johnson" <johnsonje(a)adelphia.net> wrote: >I teach 6th grade and every year my students seem to have a lot of >difficulty with fractions, specifically, reducing or recognizing that a >fraction isn't reduced. I have given them many ideas on how to tell, even >to the point of writing out the factors for both the numerator and >denominator. Does anyone have any suggestions on how to get this concept >across to the students? Any suggestions would be greatly appreciated. >Janet Johnson You could unsimplify some fractions e.g. 2/3 -> 10/15 i.e. show the inverse of what it means to "simplify". If 'prime number' is already a concept, you could try 'relative prime' meaning no factors in common (i.e. "a fraction is in lowest terms when the numerator and denominator are both integers and are relative primes"). Along these lines, I really like your idea of writing out the prime factors, crossing out those in common e.g.: 150/210 -> (3 x 5 x 2 x 5) / (7 x 3 x 2 x 5) -> 5/7 That ties back to "intersection of sets" i.e. the intersection of {3,5,2,5} and {7,3,2,5} is {3,5,2} (multiple appearances of the same factor constitute unique members of each set). As the other poster mentioned, you're looking for the greatest common divisor or "biggest gzinta (goes into)", in the above example 3 x 2 x 5 = 30. Pictorially, you could do a pie divided into 3 wedges (thirds) and then slice each third in half (sixths). Getting 1/3 of the pie is the same as getting 2 x 1/6s or 2/6s. Lots of pictorials along these lines -- including in 3D (i.e. volumes in space).[1] Historically speaking, finding the greatest common divisor (gcd) is one of the oldest algorithms on record, and is credited to Euclid. Here's how Euclid did it: Setup: Consider two numbers a and b. Which is greater? Lets say a (call the other one b). Step 1: Divide a by b. Step 2: If it goes evenly (remainder = 0), we're done, and b is the gcd. Step 3: If there's a remainder r > 0, then we can refocus the problem to finding the gcd between b and r. So rename b, r to a,b and loop to step 1. Note that 1 always goes evenly, so if the remainder is 1 in Step 3, we'll get 1 as the answer in Step 2 -- which is OK. A gcd of 1 means a,b are relative primes. Trying the above with b=150 and a=210 i.e. gcd(210,150): Step 1,2: 210/150 -> remainder of 60 Step 3: now find gcd(150,60) Step 1,2: 150/60 -> remainder of 30 Step 3: now find gcd(60,30) Step 1,2: 60/30 -> remainder of 0, so answer is 30 In a well-equipped math classroom, one with an internet hookup and a projected computer screen (big up front), I'd show students (even 6th graders) some of these ideas using Python notation (a free download, no strings attached).[2] You can use the % primitive to get the remainder, i.e. a%b -> remainder of a divided by b. Here's what that looks like (>>> is the prompt (teacher types), with the next line, in a different color, being Python's reply): Python 1.6a2 (#0, Apr 6 2000, 11:45:12) [MSC 32 bit (Intel)] on win32 Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam IDLE 0.6 -- press F1 for help >>> 210%150 60 >>> 150%60 30 You could even show a little program implementing Euclid's algorithm. Here's one way to write it: >>> def gcd(a,b): while 1: # loop until break r = a%b # step 1 if r == 0: # step 2 break # we're done else: a,b = b,r # step 3 return b >>> gcd(210,150) 30 Here's another way (even shorter): >>> def gcd(a,b): r = a%b # step 1 if r == 0: # step 2 return b else: return gcd(b,r) # step 3 >>> gcd(210,150) 30 It's fun to have a computer in the picture because then you can play with larger numbers than in the text books, or than calculators can handle. For example: >>> gcd(72534982347852342L,6276912736644L) 6L The L mean "long integer" and cues Python that we're going beyond the scope of "ordinary" integers (a type casting consideration handled more transparently in another language, also a free download, DrScheme).[3] Here's one way to write gcd using DrScheme: Function: ; gcd: number number -> number ; to find the gcd of two numbers (Euclid's Algorithm) (define (gcd a b) (define r (remainder a b)) (cond [(= r 0) b] [else (gcd b r)]) ) Usage: Welcome to DrScheme, version 101. Language: Textual Full Scheme (MzScheme). > (gcd 210 150) 30 > (gcd 72534982347852342 6276912736644) 6 So the above gcd means: 6276912736644/72534982347852342 -> (6 x 1046152122774)/(6 x 12089163724642057) [practice long division!] -> 1046152122774/12089163724642057 and 1046152122774, 12089163724642057 should be relative primes, since we've already divided by the gcd. Checking: Python: >>> gcd(12089163724642057L, 1046152122774L) 1L DrScheme: > (gcd 12089163724642057 1046152122774) 1 Yep! Long division problem (good to show because calculators and even floating point processors choke on this many digits, but our paper and pencil algorithms do not): 12089163724642057 ------------------ 6|72534982347852342 Doing a long divisions such as the above on paper needn't be too tedious if the whole class works together a few times. Good review of the times table for 6. I teach putting the remainder as a tiny digit to the upper left of the next, so we don't have this huge long series of subtractions trailing down like the tendrils of a jelly fish. E.g. 6|7... leaves 1, so the 1 goes to the upper left of the 2, making 12, and so on (I'm sure all the K-12 math teachers know what I mean). I think it's important to clue kids early about these limitations of floating point and even long integer arithmetic on computers, plus most calculators won't even touch 17-digit numbers (or greater). As I wrote re the Math Summit in Oregon (1997): "(as the official note taker, I managed to interject twice -- once about the wierdnesses in floating point math as implemented in computers, reason enough to learn the algorithms on paper as well)"[4] I.e. this is how to respond to students who ask why we're still learning long division on paper when we have calculators and computers: because calculators wimp out, and with computers you may need to check its math, especially if any floating point operations were involved. For example in Python, using floating point: >>> 72534982347852342.0/6.0 12089163724642056.0 Which is off by a digit (because of the limited precision of floating point numbers). DrScheme gives the same answer, but warns the result is imprecise using the # symbol. From the manual: * Print inexact numbers with #i -- Prints inexact numbers with a leading #i to emphasize that they represent imprecise results (or even effectively incorrect results, depending on the intended calculation). > 72534982347852342/6.0 #i12089163724642056.0 If the above were really the right answer, then 72534982347852342 should be divisible by 36, since 12089163724642056 is again divisible by 6. Python might lead us to believe this is true, because the / operator is designed to give only integer answers no matter what -- unless one of the arguments is floating point (i.e. we'll get the wrong answer whether we use / as an integer or floating point operator in this case). So: >>> 72534982347852342L/36L 2014860620773676L -- but we can't really trust this result. The way to check is to ask for a remainder is to use the % operator: >>> 72534982347852342L%36L 6L .... which shows 36 isn't really a 'gzinto'. DrScheme doesn't implement the / operator in the same way, and 72534982347852342/36 gives a correct answer, a fraction: > 72534982347852342/36 12089163724642057/6 Kirby [1] Too much emphasis on cubes and rectangular prisms when doing fractions leaves students deprived of a stronger conceptual grasp of polyhedra, which derives from using a richer set of fractional relationships. My school is very much into using a modularized set of polyhedra with easy whole number and fractional relationships, as per my web pages: http://www.teleport.com/~pdx4d/volumes.html [2] http://www.python.org/sigs/edu-sig/ [3] http://www.cs.rice.edu/CS/PLT/Teaching/ [4] http://www.teleport.com/~pdx4d/mathsummit.html ---------------------------- submissions: post to k12.ed.math or e-mail to k12math(a)sd28.bc.ca private e-mail to the k12.ed.math moderator: kem-moderator(a)thinkspot.net newsgroup website: http://www.thinkspot.net/k12math/ newsgroup charter: http://www.thinkspot.net/k12math/charter.html

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Numpy 16.0 binaries available? (Win32)
by Keith Farmer Sept. 14, 2000

Sept. 14, 2000

Attempting to locate binaries of Numpy 16.0 for Win32. Anybody have them? Keith Farmer deoradh(a)yahoo.com

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