Mailman 3 June 2011 - Edu-sig

[ANNC] pynguin-0.10 python turtle graphics application
by Lee Harr 25 Jun '11

25 Jun '11

Pynguin is a python-based turtle graphics application. It combines an editor, interactive interpreter, and graphics display area. It is meant to be an easy environment for introducing some programming concepts to beginning programmers. http://pynguin.googlecode.com/ This release continues to expand basic functionality and explores more user-friendly options in the interface. Pynguin is tested with Python 2.7.1 and PyQt 4.8.3 and will use Pygments syntax highlighting if available. Pynguin is released under GPLv3. Changes in pynguin-0.10: Session - can now save to or load from directory instead of a file - remember drawing speed between sessions - remember avatar setting between sessions Pynguin API - allow setting drawing speed from code - add xyforward(dist) method to return coords dist ahead of pynguin - reset() is more thorough restoring pynguin to initial state - handle input() and raw_input() properly - simple onclick() handler only affects the main pynguin - onclick() responds to right-click now (not left-click) Canvas - use left mouse button to pan/drag the canvas - mouse wheel zooms around cursor - added menu entries and shortcuts for panning canvas - added menu item for tracking pynguin - recenter canvas on home() and reset() - fixed crash on startup when pynguin tracking is enabled - all canvas related shortcuts now use Alt-<key> Integrated Editor - added ability to open plain python files - can monitor file for changes made in external editor - removed "Remove" button from under editor - added warning when removing page with menu option - all editor related shortcuts now use Ctrl-<key> - Ctrl-N is now for new editor page, not new Pynguin file - added shortcuts for switching docs - added shortcut for Test/run code Integrated Console - added Ctrl-<space> shortcut to toggle between editor/console Examples - improved threaded examples - can start pynguin moving in one separate thread and get cursor back to do something else in a new thread - improved multi examples - implements the same bugs() example as the threaded example but in a different style General - synchronize fill menu items when using fill() and nofill() - synchronize pen menu items when using penup() and pendown() - fixed crash trying to open non-existent file - fixed crash trying to save to non-writeable file - experimental .deb distribution format

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Re: [Edu-sig] Edu-sig Digest, Vol 95, Issue 14
by Marianne McKenna 25 Jun '11

25 Jun '11

I will be out of the office until June 27th. Please contact your building techsupport for help. If it's an emergency please contact Paul Musto or Patricia Hunter in the computer center. Many Thanks!

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Inexpensive robot teaching platforms
by Blake Elias 24 Jun '11

24 Jun '11

My high school competes in the FIRST Robotics Competition. Every year we have to teach new members basic robotics and programming concepts, to get them excited and prepared for the heat of competition. Those who have the patience stay with it and have a great time, but we always lose a bunch of people partly because the lessons are not very interesting or useful. I believe the solution is to teach with small robots, instead of just writing on the board and doing "hello world"-type programs. Vern, I was very inspired by your PyCon talk on teaching programming with the Scribbler. I know people have had success with it, it looks like a great robot to teach with. For our budget however, getting a bunch of these would be a stretch (I think the scribbler + fluke board combo costs $140 -- is this correct?). You do need the Fluke board unless you want to program it in BASIC Stamp or their GUI, right? I've seen some cheaper mini-robots but I'm not sure if they're any good. Does anyone have suggestions? Thanks, Blake Elias

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Re: [Edu-sig] Edu-sig Digest, Vol 95, Issue 13
by Marianne McKenna 24 Jun '11

24 Jun '11

I will be out of the office until June 27th. Please contact your building techsupport for help. If it's an emergency please contact Paul Musto or Patricia Hunter in the computer center. Many Thanks!

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Math UI
by Jay Bloodworth 18 Jun '11

18 Jun '11

This question is not really specific to python. Apologies if that is a party foul, but I think it is in the spirit of the list. Suppose I give an algebra student the system: y=2/3x + 5 4x - 2y = 7 I want the student to solve the system algebraically, to show her work, to use appropriate notation, and to do it on a tablet computer rather than pencil and paper. What does the UI look like for this task? Is it something the equation editor for a word processor? Or more specialized? Are their lots of menus? Or is it more like LaTeX, using special text syntax to denote fractions, etc. How do we make sure that using the UI doesn't occupy so many brain cycles that it limits the student's ability to do the algebra? Obviously this is less about solving systems in particular and more about the issues that come up as computers begin to replace pencil and paper as the standard format for communicating in a math classroom. I would appreciate your thoughts. Jay

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More practice exercises
by Gregor Lingl 11 Jun '11

11 Jun '11

A very interesting collection of exercises you can find on http://projecteuler.net/ Especially the problems below 100 are well suited for beginners. http://projecteuler.net/index.php?section=problems This week's problem, on the contrary, seems to be customized for Kirby! http://projecteuler.net/index.php?section=problems&id=342 Best regards, Gregor

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Re: [Edu-sig] this is interesting
by Laura Creighton 08 Jun '11

08 Jun '11

In a message of Tue, 07 Jun 2011 21:51:31 PDT, michel paul writes: >>> def f(n, history = []): > history.append(n) > return history <snip> > >What's a good way to explain what's going on? > >- Michel Assuming that you have already taught about the difference between mutable and immutable objects, ask the student to make a different version, with the signature def f2(n, history=()) and see if that gives the expected result. Then get the student to _explain to you_ what's the difference between tuples and lists that could result in this difference in behaviour. This will move the discussion one of two ways. Either to "why using default values for mutable objects in function signatures is almost never what you want to do, and a discussion of what we can do about this (use sentinels)" :-) or "lists are a bad idea, use tuples for everything" :-(. If you are in conversation 2, you need to detour through 'then why do we have a list datatype? What is it good for?" Laura

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this is interesting
by michel paul 08 Jun '11

08 Jun '11

>> def f(n, history = []): history.append(n) return history >>> f(1) [1] >>> f(2) [1, 2] >>> f(3) [1, 2, 3] >>> f(2) [1, 2, 3, 2] >>> f(1) [1, 2, 3, 2, 1] >>> f(1,[]) [1] A student wrote me wondering why his function wouldn't 'clear' after being called. He meant to create an empty list and ended up with something like this. What's a good way to explain what's going on? - Michel -- ================================== "What I cannot create, I do not understand." - Richard Feynman ================================== "Computer science is the new mathematics." - Dr. Christos Papadimitriou ==================================

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background docs on Tractor Art
by Kirby Urner 03 Jun '11

03 Jun '11

I'm thinking OOP, more than any other paradigm, encourages a rich set of metaphors, which may be touted as an advantage if you're ever up against the well in an OOP-hostile room (been there done that). "Anti-imperativists" can be pretty militant. Inheritance is a most obvious metaphor, from whence come any number of ancestor, parent, child, multi-parent paradigms. All that assumed knowledge from "real life" infuses the shop talk, giving a boost in understanding provided the metaphors aren't too misleading. The Turtle has become ubiquitous as an obvious "self" in some environment that might in turn be subclassed if we like. Some joke about "turtles all the way down". It's the ultimate avatar or sim, usually seen as "3rd person" but could be "1st person" as well (change of viewpoint). However, I went with a Tractor instead of Turtle precisely because the turtle metaphors have been milked pretty thoroughly and needn't be the last word. With a Tractor, we get new etymologies, such as traction, tractare, to drag, to plow, to leave a rut or mark, to record, to do work (tractatus). One of the easiest ways to show off metaphors is not to subclass a the Tractor type however, but to simply rename it. Generic: >>> from farmworld import Tractor as Worker, Farm as Factory More specific: >>> from farmworld import Tractor as government_worker, Farm as Area_51 Students immediately appreciate the analogies between a horse-like fuel burning engine that does the work of hundreds of humans, being akin to some generic "doer" or "agent", with the Farm being akin to said worker's "environment" or "workplace". One is starting to think in a more OO fashion when one can mentally juxtapose what is common among objects. The Tractor class simply "mows the lawn" in an XY grid. Actually, a tractor leaves no record in the field itself (self.field is a list of lists), unless you invoke the plow method (why not plough = plow?) to make a mark (replace an ASCII character with a different one -- peek and poke come to mind, from old timer BASIC coders). Ed asked me if I'd considered Unicode for the Farm cells. Indeed, a big part of the Lessons is to mentally add a 3rd dimension to each cell. Given this is a Farm, I use the word silo, which has the interesting property of pointing either up, above the plane (a grain silo), or below (a missile silo). If this XY grid were a bitmap (BMP), or tif file, with each cell a pixel, then the silo could be about color depth. As it is, even though we're getting by with Latin-1, we can suggest a 32-bit deep silo, with various UTF encodings compressing that 32-bit pattern. The mapping to ASCII is suggestive, and the fact that we're getting by with single bytes merely highlights the primitivist aesthetic across all modules. The Tractor then needs to be subclassed. It's still an iterator, meaning it exports the iterator interface (the Java way of talking) with __iter__ and __next__. The Sensor tractor does something most Logo-based turtles don't do: it senses its environment (of course Logo lets you write these procedures right? You can query the color value at a screen position?). The Sensor tractor doesn't just look straight down, at the cell over which it sits -- (Y, X) -- it looks in the 8 directions perpendicular to the edges of a Stop sign: NW N NE E SE S SW W. If any of these happen to be off the field, there's a default value. Tractors know to StopIteration when they hit a field boundary or fence. With a Sensor Tractor, we can play Conway's Game of Life, by checking the neighborhood. Rather than subclass again, we just write a function taking Sensor tractors for granted. With a Sensor Tractor, we may also implement Wolfram's 256 rules, simply by reading the three cells to the north (NW N NE) and following some simple substitution rules. http://4dsolutions.net/ocn/python/OST/lifegame.py http://4dsolutions.net/ocn/python/OST/nks.py The CropCircle Tractor is different. It is inwardly driven by a generator for the Mandelbrot Set (others might be swapped in, as the "brains" for this Tractor). The CropCircle subclass stretches a complex plane of given size over whatever 2d array (list of lists). When its plow method is fired, it doesn't just make a mark, like the ancestor / parent. It computes a mark based on what the Mandelbrot Set would be here, after so many iterations of its generator. The resulting output, after the field has been mowed, is a Mandelbrot in rough outline, a primitive example of "ASCII art": http://4dsolutions.net/ocn/python/OST/ostcanvas.py http://www.flickr.com/photos/17157315@N00/5645244292/in/set-721576256460717… Kirby Much more about Tractors etc.: http://groups.google.com/group/mathfuture/browse_thread/thread/d2390406c11f…

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Anyone interested in discussing the turtle module?
by Jeff Elkner 03 Jun '11

03 Jun '11

Hi All, I'm working on an introductory CS book using Python with the turtle module, but I'm finding the inability of turtle.Screen() to take screen size arguments to be a real pain. The screen size appears to depend on the screen size of the host environment, which means standardizing screen shots for the book becomes impossible. Any thoughts on this issue? It would be a huge help in promoting Python's use in education if we could make use of such a potentially fine module as the turtle module, but I'm finding it very difficult to write curriculum materials that use it since students don't have control over the turtle's screen in any easy to use way. Thanks! jeff elkner open book project http://openbookproject.net

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