Mailman 3 August 2012 - Edu-sig

a short essay about programming
by kirby urner 08 Dec '22

08 Dec '22

A common "error" (not too serious) that I see in beginning Python (and no doubt other languages, but Python is the one I'm teaching), is having a while condition that appears to put a lid on things, but then the flow all leaks away through break statements, such that the "front door" condition is never revisited. while guess != secret: guess = int(input("Guess?: ") if guess == secret: print("You guessed it!") break else: print("Nope, try again...") What's messed up about the above code is you never really go back to the top in the case where you'd get to leave. Rather, you exit by the back door, through break. So in that case, wouldn't have been simpler and more elegant, even more "correct" (dare I say it) to have gone: while True: # no ifs ands or buts guess = int(input("Guess?: ") if guess == secret: print("You guessed it!") break else: print("Nope, try again...") I see lots of heads nodding, and that could be the end of the matter, but then a next question arises: wouldn't this also be a more correct solution?: while guess != secret: guess = int(input("Guess?: ") if guess == secret: print("You guessed it!") continue # instead of break else: print("Nope, try again...") We're back to having a variable while condition, not a boolean constant, but this time we actually exit by means of it, thanks to continue or... while guess != secret: guess = int(input("Guess?: ") if guess == secret: print("You guessed it!") else: print("Nope, try again...") ... thanks to no continue. This last one is getting a thumbs up, but then I'd pause here and say "continue" can be easier on the eyes. It's unambiguous where it takes you, in contrast to having to scan on down the gauntlet, looking for possibly other open doors. "What happens next" should not require scanning ahead too far. Help us not to get lost. Be a civic-minded coder. I'm thinking of a programming style that advises two things: (a) if you use a while condition that's variable, that's expected to change, then your goal should be to always exit because of that, i.e. that should be your only exit point. Even if some other criterion suggests exiting, you have the option to flip that "lid" at the top, to crack that front door, and bounce the ball out. (b) which is why 'continue' is your friend. You are showing the user where your 'break' statements are, except you don't use "break" statements, as you've given a non-constant condition, and your aim is to make that your ONLY exit point. In short: never use break to exit a while loop unless your condition is while True. Instead, always flip the condition and exit through the font door. However, as soon as I make that rule I can think of good reasons to break it. The other programmers in the room are shaking their heads. Won't we lose information, needed elsewhere in the program, if we "artificially" force a True condition to False. Aren't we, in effect, lying? That concern could be addressed. Keep all the info true, just treat the "lid condition" (it "keeps a lid on it") as a flag. Go ahead and remember the user's guess. allowed = 5 tries = 1 exit = False while not exit: # no other way out guess = int(input("Guess?: ") if guess == secret: print("You guessed it!") exit = True # instead of break continue print("Nope, try again...") tries += 1 if tries == allowed: print("You've maxed out") exit = True continue I think we all understand the main issue: writing reader-friendly code, and rules for doing so. There's something comforting about approaching a while loop and knowing its not a leaky sieve, riddled with back doors, maybe even an exit( ) time bomb. But in the recursion world we want a minimum of two exits usually: when another round is called for versus when we've "hit bottom". Can we have it both ways? Conclusions: Lets not be too hasty with rules of thumb and: Lets keep the reader in mind when writing code. Just because the interpreter knows to compute the flow unambiguously, doesn't mean all ways of writing it are equally reader-friendly. What may seem a gratuitous gesture, an unnecessary flourish, may actually promote reader comprehension of your code, and that should be a goal as much as satisfying the interpreter. Kirby

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xturtle online via processing.js !?
by Jurgis Pralgauskis 27 Sep '12

27 Sep '12

Hi, I am struggling around with interactive online py tutorials with https://launchpad.net/projects/intro-to-code (ith might become securely sandboxed soon, as pypy made it possible http://blog.sandbox.lt/en/WSGI%20and%20PyPy%20sandbox :) but one more thing is I'd like to let access xturtle functionality online - one possible way could be triggering tkinter to save its canvas to ps, and then convert them with imagemagic and show via web (animated gif or static) - but if pyjamas can render GUI for js (http://www.google.lt/search?&q=pyjamas+python ), mayby there is a way to **translate turtle commands to processing.js analogues** http://ejohn.org/blog/processingjs/ would it be difficult -- how do you think? -- Jurgis Pralgauskis tel: 8-616 77613; jabber: jurgis(a)akl.lt; skype: dz0rdzas; Don't worry, be happy and make things better ;) http://sagemath.visiems.lt

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PyCon Education Summit Update
by Vern Ceder 05 Sep '12

05 Sep '12

Hi everyone, I just wanted to bring you uptodate on where we're at with the Education Summit at the upcoming PyCon. This will be a "by invitation only" event, so if you are interested (and I haven't contacted you already) or know of someone who would be really good for and interested in this event, please let me know about that interest off list. One of our reasons for going with invitations is that we want to be sure that we get a fair balance between the various education constituencies in space available, so I can't guarantee that absolutely everyone who wants to come will be invited.... But I'll try. Also we're looking for a keynote and panelists for the topics below, so if you know of anyone that you think would be good, please email me off list. Also if you have any other suggestions or questions, please let me know. There is also a google group for announcements about the summit, so if you're interested, you should join that group - https://groups.google.com/forum/?hl=en&fromgroups#!forum/pycon-education-su… First of all, the summit blurb is the following: "In 2013, for the first time ever, PyCon will be holding a Python Education Summit. This summit will be a gathering of teachers and educators from the many venues that support the teaching of programming in Python - schools, colleges and universities, community based workshops, online programs and government. These constituencies differ widely in resources and constraints, in methods, and in goals and aspirations, yet are all working to address the same issue - a lack of coding literacy - with the same belief - that teaching programming is needed and that Python is an excellent way to do that. The goal of the summit is to bring together leaders from those diverse constituencies to learn more about each other's efforts and gain useful insight from them, to form connections that might foster future collaboration, to identify common issues and begin discussing ways to attack them, and to create an enhanced sense of unity, purpose and community among teachers of Python, wherever they might be. It is also our hope that the summit will serve as catalyst for the rest of PyCon to encourage even more interaction - hallway discussions, open spaces, lightning talks, and sprints. Anyone attending this conference will gain a broader understanding of approaches and issues in teaching Python, will have the opportunity to contribute to their discussion, and will make contacts with other teachers of Python from across the community. A high school teacher might make contacts that allow her to enlist the support of a community based program while a community volunteer might gain useful guidance on curriculum design. In addition to active involvement in the process of teaching Python, the only requirement of attendees is engagement. The morning sessions will include panel discussions that encourage participation and the afternoon will consist of unconference style breakout sessions that demand it. So please come willing to learn, to teach, and to participate." Also, I've developed a basic statement of the topics we'll be covering: "As I see it there are the three core issues that most impact Python education today: engagement, curriculum and teaching. So I'm proposing that we frame the topics for the summit accordingly. Engagement - By "engagement" I mean getting people involved - attracting learners and letting them know why they should be eager to learn Python, recruiting teachers, sponsors and supporters with the skills needed to facilitate that learning, and then keeping everyone involved in the community. You could also call this "outreach" or even "marketing". Whatever you call it, we need to attract people who want to learn Python and the people and the people to help satisfy that need. Topics: How are the various education communities attracting people to their programs? What things can each learn from other programs, particularly in terms of increasing interest and involvement in the Python language and community? Curriculum - The need for uptodate, accessible and appropriate curriculum is felt in all aspects of Python education. Community programs need free and flexible lesson plans and teaching materials, schools are often reluctant to offer a program without an established curriculum, and teachers in all areas are often desperate for curricula that can be leveraged with minimal time and effort. Topics: What curriculum materials are currently freely available for teaching Python? What means can be used to increase their quality, coverage and availablity? Teaching - Again, teaching is a universal issue. Schools often have experienced teachers, but ones who don't know Python. Community programs can find Python experts, but they frequently have little teaching experience or knowledge. Topics: what best practices might community programs follow to help volunteer teachers do a better job? Are there any teaching guildes or hints available now? What strategies might help schools qualify their current experienced teachers to teach Python? How might we increase the number of qualified teachers generally? Underlying themes: The two underlying and unifying themes for the summit are communication and collaboration." Thanks! Vern -- Vern Ceder vceder(a)gmail.com, vceder(a)dogsinmotion.com The Quick Python Book, 2nd Ed - http://bit.ly/bRsWDW

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Re: [Edu-sig] Python Installation with PyLab?
by Jeremy Bruce 24 Aug '12

24 Aug '12

So, I have iPython installed on my machine, because I did the EPD install. The notebook worked fine in Chrome...so am I to understand that it's using my local machine as an iPython server and just using the browser as the interface? How would this work with a classroom of students? Would they still all have to install EPD, or could they all run off of my server? Thanks On 2012-08-23, at 17:19 , Marc Keller <marc.keller1(a)gmail.com> wrote: > Try the IPython Notebook, it's easier to set and use than SAGE > > http://ipython.org/ipython-doc/dev/interactive/htmlnotebook.html > > On Thu, Aug 23, 2012 at 6:35 PM, Jeremy Bruce <profjeremybruce(a)me.com> wrote: > Hi Edu, > > I'm hoping to start bringing python into my math teaching in stages over the next year. > I've been trying out different installations and setups, and wondering if anyone could offer any guidance. > > Ideally, I'd have a setup that included numpy/scipy/matplotlib, but that stuff seems to be difficult to install by itself, or necessarily come along with a heavy duty installation of other things in the various distributions I've seen (SAGE, and EPD). Plus, anyone wanting to use an iPad is stuck. So, installing EPD is option 1, but has those limitations. Thoughts? > > Option 2 is just not using pylab-y stuff, and just going plain installation. Macs, PCs, and iPads could all join, and we could just use a simple text editor (I like Sublime Text 2), and the terminal. > > Option 3 is an idea from Fraser Speirs. Set up a Linux server on Amazon cloud services and have students SSH in to one installation. This also has the benefit of giving iPad users an option. > > Would love to hear the setups you all use, and any ideas you may have. > > Thanks! > > Prof. Bruce > > -- > gmail: profjbruce > twitter: profjbruce > skype: profjbruce > web: gostudious.com > > > _______________________________________________ > Edu-sig mailing list > Edu-sig(a)python.org > http://mail.python.org/mailman/listinfo/edu-sig >

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Python Installation with PyLab?
by Jeremy Bruce 23 Aug '12

23 Aug '12

Hi Edu, I'm hoping to start bringing python into my math teaching in stages over the next year. I've been trying out different installations and setups, and wondering if anyone could offer any guidance. Ideally, I'd have a setup that included numpy/scipy/matplotlib, but that stuff seems to be difficult to install by itself, or necessarily come along with a heavy duty installation of other things in the various distributions I've seen (SAGE, and EPD). Plus, anyone wanting to use an iPad is stuck. So, installing EPD is option 1, but has those limitations. Thoughts? Option 2 is just not using pylab-y stuff, and just going plain installation. Macs, PCs, and iPads could all join, and we could just use a simple text editor (I like Sublime Text 2), and the terminal. Option 3 is an idea from Fraser Speirs. Set up a Linux server on Amazon cloud services and have students SSH in to one installation. This also has the benefit of giving iPad users an option. Would love to hear the setups you all use, and any ideas you may have. Thanks! Prof. Bruce -- gmail: profjbruce twitter: profjbruce skype: profjbruce web: gostudious.com

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Re: [Edu-sig] [ANNC] pybotwar-0.8
by Terry Reedy 16 Aug '12

16 Aug '12

On 8/16/2012 11:40 AM, Ramchandra Apte wrote: > Look you are the only person complaining about top-posting. No he is not. Recheck all the the responses. > GMail uses top-posting by default. It only works if everyone does it. > I can't help it if you feel irritated by it. Your out-of-context comments are harder to understand. I mostly do not read them. -- Terry Jan Reedy

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Re: [Edu-sig] [ANNC] pybotwar-0.8
by Mark Lawrence 16 Aug '12

16 Aug '12

and "bottom" reads better than "top" On 16/08/2012 15:37, Ramchandra Apte wrote: > nah.. "war" sounds better than "contest" > > On 16 August 2012 14:59, Jean-Michel Pichavant <jeanmichel(a)sequans.com>wrote: > >> Lee Harr wrote: >> >>> pybotwar is a fun and educational game where players >>> write computer programs to control simulated robots. >>> >>> http://pybotwar.googlecode.**com/ <http://pybotwar.googlecode.com/> >>> >>> >>> The focus of this release is making all functionality >>> available from the PyQt interface and making PyQt >>> the default interface. >>> >>> pybotwar uses pybox2d for the physical simulation. >>> It can be run in text-only mode -- useful for longer >>> tournaments -- or use pyqt or pygame for a graphical >>> interface and visualization of the action. >>> >>> pybotwar is released under GPLv3. >>> >>> >>> Changes in pybotwar-0.8: >>> - pybox2d-2.0.2b2 is now the required version >>> >>> API >>> - Robot.turret() now takes turret speed instead of angle >>> - PING sensor now differentiates own bullets from enemy bullets >>> - PING differentiates dead robots when remove_dead_robots=False >>> - made internal Robot state variables less likely to conflict with >>> user code >>> >>> Settings >>> - added "robots dir" setting to make it easier to run pybotwar >>> from an installed copy, rather than from the unpacked folder >>> - logs, lineups, and db all go in robots dir >>> - robot modules are now loaded by full path >>> - If using Qt settings, remembers most recently used set of robots >>> >>> PyQt4 Interface >>> - PyQt4 view mode is now the default >>> - (text mode and pygame/pygsear still available) >>> - all settings are available from PyQt interface >>> - remembers most recently used set of robots >>> - added debug window showing sensor values, commands, and logs >>> - can now start tournaments (and multiple battles) from pyqt >>> - can also start tournaments to run in background >>> - editor automatically adds .py to robot filename if needed >>> >>> Other changes >>> - made template.py a valid robot program >>> - single battles are now run as 1-battle tournaments >>> - renamed kill stat to outlasted >>> - started tracking kills as dealing final damage to other robot >>> - commandline can now take a list of robots to load >>> - added "Super Tournaments" >>> - runs tournaments with all possible combinations of robots >>> >>> Fixes: >>> - made POSition sensor scale same as PING sensor >>> - fixed editor backspace between left edge and start of text >>> - fixed inability to re-open file once its window was closed >>> - fixed crash when cancelling file-open dialog >>> - limited motor speed on turret >>> - log messages in testmode when using qt4 view >>> - fall back to :memory: database if unable to open db file >>> >>> >>> >> I have some suggestions: >> >> - rename pybotwar into pybotcontest >> - replace "bullet" by "missile of passion" >> - replace "dead" by "overflood with love" >> - "PING sensor" into "pheromone sensor" >> ... and so on :p >> >> JM >> >> -- >> http://mail.python.org/**mailman/listinfo/python-list<http://mail.python.org/mailman/listinfo/python-list> >> > > > -- Cheers. Mark Lawrence.

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[ANNC] pybotwar-0.8
by Lee Harr 15 Aug '12

15 Aug '12

pybotwar is a fun and educational game where players write computer programs to control simulated robots. http://pybotwar.googlecode.com/ The focus of this release is making all functionality available from the PyQt interface and making PyQt the default interface. pybotwar uses pybox2d for the physical simulation. It can be run in text-only mode -- useful for longer tournaments -- or use pyqt or pygame for a graphical interface and visualization of the action. pybotwar is released under GPLv3. Changes in pybotwar-0.8: - pybox2d-2.0.2b2 is now the required version API - Robot.turret() now takes turret speed instead of angle - PING sensor now differentiates own bullets from enemy bullets - PING differentiates dead robots when remove_dead_robots=False - made internal Robot state variables less likely to conflict with user code Settings - added "robots dir" setting to make it easier to run pybotwar from an installed copy, rather than from the unpacked folder - logs, lineups, and db all go in robots dir - robot modules are now loaded by full path - If using Qt settings, remembers most recently used set of robots PyQt4 Interface - PyQt4 view mode is now the default - (text mode and pygame/pygsear still available) - all settings are available from PyQt interface - remembers most recently used set of robots - added debug window showing sensor values, commands, and logs - can now start tournaments (and multiple battles) from pyqt - can also start tournaments to run in background - editor automatically adds .py to robot filename if needed Other changes - made template.py a valid robot program - single battles are now run as 1-battle tournaments - renamed kill stat to outlasted - started tracking kills as dealing final damage to other robot - commandline can now take a list of robots to load - added "Super Tournaments" - runs tournaments with all possible combinations of robots Fixes: - made POSition sensor scale same as PING sensor - fixed editor backspace between left edge and start of text - fixed inability to re-open file once its window was closed - fixed crash when cancelling file-open dialog - limited motor speed on turret - log messages in testmode when using qt4 view - fall back to :memory: database if unable to open db file

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teaching in a classroom again...
by kirby urner 06 Aug '12

06 Aug '12

I've again been teaching teens, no my usual practice these days, but a fun variation on the theme. Saturday Academy kids are self selected and tend not to have ego problems around whether they're "smart enough" or whatever it takes. The all believe they have the "right stuff" ultimately. The classroom is probably the best I've had, in terms of being able to project content on the big screen. I have a button to lower the blinds. I used to think Hewlett-Packard would go into the classroom design business as there's more one could do. Once could have a button to project each student's console to the front, for example, perhaps under the teacher's control. That takes software, not just hardware. You'd need to work it out from the ground up. Ideally, the school is build like a theater or holodeck, to accommodate all sorts of classroom configurations. Of course we don't really have such schools today, unless you count Universal Studios. I've uploaded some pix to Flickr: http://www.flickr.com/photos/kirbyurner/7680435316/in/photostream http://www.flickr.com/photos/kirbyurner/7680433664/in/photostream/ (etc. to the left and right of those) These are middle school aged, so like averaging 14 or so years old. What I do is intersperse mini-talks on Python with hands on play with showings of Youtubes. Yesterday we zoomed in on Mandelbrot sets before lunch, then switched to Mandelbulb fly-throughs after lunch. I have them for two hours, with a lunch break in between of under an hour. The title of the course is 'Martian Math and Programming in Python'. The Martian part is rather subtle in that I just plant some ideas. I bring a large tetrahedron to the room, plus carry it through the halls, turning heads. In other versions of this course I might dwell on a particular storyboard / story problem wherein Earthlings and ETs are working together on a big dam (hydro-electric) but measure concrete in different units (cube vs tetrahedron respectively). Here's some code I'll be taking on memory stick today, reviewing some of what we've been doing. We're using Python 2.7 + VPython on Win7. === """sa1.py""" from visual import * import math def ballmatrix( ): for x in range(-10, 10): for y in range(-10, 10): sphere(radius=.5, pos=(x,y,0)) def hidef( ): for x in range(-100, 100): for y in range(-100, 100): sphere(radius=.5, pos=(x,y,0)) def mandelbrot( ): for r in range(-40, 10): for i in range(-20, 20): c = complex(r/10.0, i/10.0) z = 0 for times in range(10): z = z*z + c if abs(z) < 1: sphere(radius=.5, pos=(r,i,0), color = color.black) else: sphere(radius=.5, pos=(r,i,0), color = color.red) def mandelbrot2( ): for r in range(-40, 10): for i in range(-20, 20): c = complex(r/10.0, i/10.0) z = 0 for times in range(10): z = z*z + c thelength = abs(z) if thelength < 1: sphere(radius=.5, pos=(r,i,0), color = color.black) elif 2 >= thelength >= 1: sphere(radius=.5, pos=(r,i,0), color = color.red) elif 5 >= thelength >= 2: sphere(radius=.5, pos=(r,i,0), color = color.orange) elif 20 >= thelength >= 5: sphere(radius=.5, pos=(r,i,0), color = color.green) else: sphere(radius=.5, pos=(r,i,0), color = color.blue) mandelbrot2() === """ sa2.py """ from visual import * import math """ color = (r, g, b) where r,g,b are between 0 and 1. red green blue """ def colorchange(): g, b = 0, 0 for r in range(0, 100): # increase red from 0 to 1 ball = sphere(radius=10, color=(r/100.0, g, b)) rate(50) ball.visible = False del ball r, b = 1, 0 for g in range(0, 100): # increase green from 0 to 1 ball = sphere(radius=10, color=(r, g/100., b)) rate(50) ball.visible = False del ball g, b = 1, 1 for b in range(0, 100): # increase blue from 0 to 1 ball = sphere(radius=10, color=(r, g, b/100.)) rate(50) ball.visible = False del ball ball = sphere(radius=10, color=(1,1,1)) # white colorchange() === """ sa3.py """ from visual import * import math from random import randint def say_something(): """ Get something from the user to display """ saywhat = raw_input("What shall I print? ") text(text=saywhat, align='center', depth=-0.3, color=color.green) def rand_color(): """ pick three random numbers between 0 and 1, e.g. 0.5 or 0.3 """ r = randint(0,100)/100. g = randint(0,100)/100. b = randint(0,100)/100. return (r,g,b) def say_alphabet(): x = -25 # offset to the left for c in "ABCDEFGHIJKLMNOPQRSTUVWZYZ": # jump through each letter text(text=c, pos=(x,0,0), align='center', depth=-0.3, color=rand_color()) x = x + 1.5 # to the the right a bit say_alphabet() # change this to point to different functions at runtime Kirby

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