Mailman 3 April 2003 - Edu-sig

looking for help with Jython...
by luby liao July 25, 2003

July 25, 2003

Jeffrey, try this: 1. change first line to public class Vehicle { 2. shell> javac Vehicle.java 3. shell> jython [liao@zen tmp]$ jython Jython 2.1 on java1.3.1 (JIT: null) Type "copyright", "credits" or "license" for more information. >>> import Vehicle >>> v = Vehicle(3,5,6) >>> v Vehicle@3f1179 >>> cheers, Luby > I'm in the middle of learning some Java to get ready for next year's AP > CSC course. I would like to make good use of the Python my students > already know, and I was thinking that Jython might offer some > interesting educational opportunities. > > What I would most like to be able to do is to import Java classes into > Python in order to be able to "play around" with them in the > interpreter. So far, I have not been able to make this work. I'm > starting with a simple example from our book: > > > class Vehicle { > public int passengers; > public int fuelcap; > public int mpg; > > public Vehicle(int p, int f, int m) { > passengers = p; > fuelcap = f; > mpg = m; > } > > public int range() { > return mpg * fuelcap; > } > > public double fuelneeded(int miles) { > return (double) miles / mpg; > } > } > > (Actually, I added all the "public"s because otherwise Jython couldn't > see them when I did: > > import Vehicle > > How can I create a Vehicle object inside of Jython? > > Thanks! >

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re: Python as a first-year programming language
by Toby Donaldson May 9, 2003

May 9, 2003

> >One of the problems I have about acceptance of Python is that the choice > >of first-year programming language is likely to be a group decision, and > >Python, for all its merits, is either unknown, or has a reputation as > >being "just a scripting language", or just a new version of BASIC. Such > >innuendos unfortunately often carry the day in many academic > >departments, as nobody but the teachers of the programming class will > >have time to actually evaluate the different languages. Who says > >academia has no pointy-haired bosses? :-) > > Seems to me that the fact that Peter Norwig chose to illustrate > the algorythms of > > > Artificial Intelligence: A Modern Approach > > > Second Edition > > by *StuartRussell <http://www.cs.berkeley.edu/%7Erussell>* and > *PeterNorvig <http://www.norvig.com>* > > in Python should say a lot to some of these folks. > > http://www.norvig.com/python/python.html > > Art > > PS Not to worry, I'm handling the errata ;) The problem with AI is that it is too complex for beginning programmers. I have enough trouble teaching it to graduate students. :-) I've used some of Norvig's code in a planner I've written in Python. It's been *great* for prototyping, like Scheme in many respects, but easier to read and write. Is there any way in Python to implement non-deterministic programming, e.g. for backtacking? It would be nice to be able to write something like this: def triple(a, b, c, n): a = choice(n) # choice non-deterministically chooses a number from 0 to n-1 b = choice(n) c = choice(n) if a**2 + b**2 == c**2: return a, b, c More practically, what would help sell Python as a teaching language at my university is: - good textbooks for it, including exercises with answers, labs, self-tests, etc. (when there's 200+ students in one class, you need self-contained materials) - explanations of the advantags it gives to "CO-OP" students, i.e. students who alternate school terms with work terms; the practicality of Python is key to selling it to student, parents, advisors, and employers, although a common argument is that we should be teaching the exact same languages that CO-OP employers use (I don't agree with that argument, but it's made all the time) - explanations of how it impacts later traditional computer science courses, such as data structures and algorithms, operating systems, graphics, etc.; there's FUD among some that teaching students a "weird" language hurts them in later courses Toby

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re: Notes from "Daddy, Are We There Yet?"
by Arthur April 30, 2003

April 30, 2003

>Squeak looks very interesting but it is a pity that the Apple license >it uses is not a real Free Software license. I'll stick to python that >is real Free Software. But I did call off my boys since Kay left Disney. That is I no longer hyperventilate at the mention of Squeak. I wish Kay was indiscrete enough to speak about his tenure there. Art

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a question on java attributes vs. python
by ali April 30, 2003

April 30, 2003

is there a python counterpart for the declaration of class attributes in java like static, private, protected???

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re: Notes from "Daddy, Are We There Yet?"
by Arthur April 30, 2003

April 30, 2003

>Notes from "Daddy, Are We There Yet?" >Alan Kay's talk at O'Reilly Emerging Technology Conference 2003 >Cory Doctorow >http://craphound.com/kayetcon2003 Wonderfully interesting exchange. Especially the "exchange" part. Jason's back. Art

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looking for help with Jython...
by Jeffrey Elkner April 30, 2003

April 30, 2003

I'm in the middle of learning some Java to get ready for next year's AP CSC course. I would like to make good use of the Python my students already know, and I was thinking that Jython might offer some interesting educational opportunities. What I would most like to be able to do is to import Java classes into Python in order to be able to "play around" with them in the interpreter. So far, I have not been able to make this work. I'm starting with a simple example from our book: class Vehicle { public int passengers; public int fuelcap; public int mpg; public Vehicle(int p, int f, int m) { passengers = p; fuelcap = f; mpg = m; } public int range() { return mpg * fuelcap; } public double fuelneeded(int miles) { return (double) miles / mpg; } } (Actually, I added all the "public"s because otherwise Jython couldn't see them when I did: import Vehicle How can I create a Vehicle object inside of Jython? Thanks! -- Jeffrey Elkner <jeff(a)elkner.net> Open Book Project <http://ibiblio.org/obp>

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re: Notes from "Daddy, Are We There Yet?"
by Arthur April 30, 2003

April 30, 2003

I had written - >Wonderfully interesting exchange. Especially the "exchange" part. And which led me to this essay by Edsger W.Dijkstra, 18 June 1975 "How do we tell truths that might hurt" http://www.cs.virginia.edu/~evans/cs655/readings/ewd498.html I like the tone, more than I probably should. To those who have studied CS in some formal way Dijkstra might be old hat. The fun for me is that so much of this old hat stuff is new ground. It does stike me that in all the discussion here about mathematics and programming, mathematics vs programming, programming with and without mathematics - there has never been a reference to the insistence of someone like Dijkstra that programming is plain and simple a branch of applied mathematics - in fact the most difficult one. "The easiest machine applications are the technical/scientific comnputations". Which rings true. If I am understanding the point, anyway. PyGeo is in a sense a program to do technical/scientific computations (and draw them). It makes sense that as a beginner, I tackled what was easiest. Again, if I am understanding the point correctly, it lends support to a notion of starting with programming and computational mathematics. Because it is the easiest, and that, under common sense ideas, is normally where one starts. Art

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re: Python as a first-year programming language
by Toby Donaldson April 29, 2003

April 29, 2003

Kirby, I agree with pretty much everything you say. It would help a lot if Zope Labs or ActiveState dropped a few million dollars each into a Python marketing campaign. Maybe we could take up a collection. :-) By the way, for a totally unrelated reason, I happened across your "Getting Serious about Series" page (http://www.inetarena.com/~pdx4d/ocn/numeracy0.html) when I was playing with sums of triangular numbers. Very nice! Toby

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Re: re: Python as a first-year programming language (Terry Hancock)
by Toby Donaldson April 29, 2003

April 29, 2003

On Monday 28 April 2003 09:29 am, Kirby Urner wrote: > > On Monday 28 April 2003 01:37 am, Toby Donaldson wrote: > > Is there any way in Python to implement > non-deterministic > > > programming, e.g. for backtacking? It would be nice to > be able to write > > > something like this: > > > > > > def triple(a, b, c, n): > > > a = choice(n) # choice non-deterministically > chooses a number from 0 > > > to n-1 > > > b = choice(n) > > > c = choice(n) > > > if a**2 + b**2 == c**2: > > > return a, b, c > > > > You're asking if Python can do pseudo-random numbers? > > Assuming that you *did* mean this, Toby, you should be aware > that your function can be written almost exactly as you > just did: > > from random import choice > > def triple(n): > a = choice(range(n)) > b = choice(range(n)) > c = choice(range(n)) > if a**2 + b**2 == c**2: > return a, b, c > > Try it. ;-) > >>> triple(3) > >>> triple(3) > (2, 0, 2) > >>> triple(3) > (1, 0, 1) > >>> triple(3) > >>> triple(3) > (0, 0, 0) Actually, I mean non-deterministic in the sense of backtracking, as in Prolog. For instance, it would be nice if I could write this def triple(n): # doh: had extraneous parameters in the original version a = choice(n) # non-deterministically chooses a number from 0 to n-1 b = choice(n) c = choice(n) if a**2 + b**2 == c**2: return a, b, c and use it like this: >>> fn = triple(4) >>> fn.next() (0, 0, 0) >>> fn.next() (0, 1, 1) >>> fn.next() (0, 2, 2) ... etc. ... The pseudocode in Norvig & Russel's AI book (1st edition, at least) uses "choice" to make certain algorithms must shorter looking. Scheme lets you implement this in about a dozen lines of code. It comes for free in Prolog. This is one reason why Scheme and Prolog are so wicked cool. :-) See http://mitpress.mit.edu/sicp/full-text/book/book-Z-H-28.html#%_sec_4.3 for more details ... Actually, Python's list comprehensions and generators, can get you close in some cases. The above triple function can actually be implemented like this: def triple(n): """ Generates all Pythagorean triples a, b, c such that: - a^2 + b^2 = c^2 - a in range(n), b in range(n), c in range(n) """ for a in xrange(n): for b in xrange(n): for c in xrange(n): if a ** 2 + b ** 2 == c ** 2: yield a, b, c Toby

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re: 3d in Python
by Arthur April 29, 2003

April 29, 2003

Dethe asks: >Is there any reason you can't drive VPython with XML-RPC? Why do you need SVG? That's really the question I am tryin to get to - is that a possiblity worth investigating. VPython is all the 3d functionality I really require - though there is always a wish list. But XML-RPC is little more than an acronym to me at this point. *If I knew, or at least had reason to believe, that I could in fact drive VPython remotely with XML-RPC, I'd dig in. Can I take you post as an opinion that there is something to be done along these lines? Can you describe how it might be configured/architected - in very, very broad terms? Most of the other tools you refer to, I am familiar with. It was actually through PyOpenGL that I became aware of and involved with using Python. My interest was in learning to work with the OpenGL API without wading through all kinds of windowing APIs to get there. The insanity one needs to go through to get a Windows window prepared for an OpenGL dot, is almost funny. Anti-intuitive is an understatment. The code, to me, looks like a random letter generator at work. Most of the other apps and APIs you reference are overkill for my needs. VTK is awesome, but considerably more than I require. Art *

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