Mailman 3 May 2017 - Edu-sig

a short essay about programming
by kirby urner Dec. 8, 2022

Dec. 8, 2022

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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MineCraft with Python
by Jurgis Pralgauskis Dec. 4, 2022

Dec. 4, 2022

Hi, intro: many kids like MineCraft :) probably you know/heared of MineCraft Pi https://www.raspberrypi.org/learning/getting-started-with-minecraft-pi/ But there seems to be Py for real MC http://coderdojotc.readthedocs.io/projects/python-minecraft/en/latest/ http://www.instructables.com/id/Python-coding-for-Minecraft/ PS.: a nice article (from js4MC world) https://github.com/walterhiggins/ScriptCraft/blob/master/docs/YoungPersonsG… -- Jurgis Pralgauskis tel: 8-616 77613; Don't worry, be happy and make things better ;) http://galvosukykla.lt

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turtle coordinates: Y increase downards - as in most graphics API?
by Jurgis Pralgauskis July 3, 2018

July 3, 2018

Hi, usually in computer graphics Y is counted to increase downwards. I casn do it with: setworldcoordinates(0, 400, 600, 0) but then, "right(..)" turns to the left :/ I could swap: right, left = left, right but on errror I get a bit misleading message >>> right() Traceback (most recent call last): File "<pyshell#10>", line 1, in <module> right() TypeError: left() takes exactly 1 argument (0 given) I thought to make this hack for kids, so better clearer error msgs... Any Ideas? Thanks :) -- Jurgis Pralgauskis tel: 8-616 77613; Don't worry, be happy and make things better ;) http://galvosukykla.lt

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My 11 year old
by Steve Eilertsen May 30, 2017

May 30, 2017

Thought I would share this story. I have been teaching my son to edit existing Python programs (rather than starting from scratch). He bought a "Farm Expert 2017" - a complex 'FarmVille" type program. He discovered to his delight that it was written in Python and was able to edit the amount of money in his "account" to serval trillion dollars - now his farm looks like the Dallas Ranch of the 1980's. Silly things like this can motivate a boy far more than any other more logical argument as to why coding is a beneficial skill to develop. So this weekend it was learning to soldier as he now has all sorts of ideas to automate his room using his Rpi which he got for his birthday last week. -- Regards Steve Eilertsen

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Python and 3D
by kirby urner May 30, 2017

May 30, 2017

> > One of the themes / questions was "how do we sustain / build on the > energy we DO have?" and I figure one way is to simply stay in touch > and inform each other of possible opportunities -- software, events, > collaboration, internships for students, etc. Novel, right? ;-) Just > call me Captain Obvious. > Good to hear from you Kevin. Did we get to talk at Pycon? I met up with Jeff Elkner at long last. Naomi and I waved at each other a couple times. Today I'm helping an old college roommate, now a tenured physics professor, get VPython up and running in a Linux context (without wine, the Windows emulator). A perennially useful theme on edu-sig, especially these days when subscribers like Wes bring big knowledge to the scene, is taking stock, taking inventory, regarding what our assets are w/r to very specific niche areas. For example: what does Python have to offer in the 3D graphics department, where the latter breaks down into "rendered" (still) and "real time" (interactive)? I think we can start out by agreeing there's nothing in the Standard Library for this. My focus since the 1980s has been spatial geometry, as in polyhedrons, as in tetrahedron, cube, and so on. That's what brought me to Python in the first place, ditto the late Arthur Siegel of Pygeo fame (see early edu-sig archives). Now it so happens that many elementary mathematics curricula do not do much with spatial geometry. When first introduced formally, geometry often tends to be planar. Calculators, even graphing ones, are poor at 3D, which might be one reason for sticking to XY plots. Polyhedrons, if present, often appear towards the back of the textbook and their treatment extends to a few surface area and volume formulas. No "dual" as a concept, no V + F == E + 2, no Descartes' Deficit, no space-filling. My pilot math curriculum (Oregon Curriculum Network website) in contrast has always featured polyhedrons right from the top. We can call them "shapes" of the word "polyhedron" seems too difficult. By the time we get to learning to code, we're able to handle these longer words. :-D Anyway, that's an invitation to start a thread. Kirby

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So. PyCon inspired me to once again join this list.
by Kevin Cole May 29, 2017

May 29, 2017

I'm not an educator by formal training, but I like to think I'm fairly good at tutoring / mentoring, and I haven't had any complaints. ;-) I remember better Education Summits... This one was okay, but it seems to me there was a lot more energy in Chicago several years back... One of the themes / questions was "how do we sustain / build on the energy we DO have?" and I figure one way is to simply stay in touch and inform each other of possible opportunities -- software, events, collaboration, internships for students, etc. Novel, right? ;-) Just call me Captain Obvious. In any case, that's what I hope to bring to the table, such as it is.

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Pycon postings...
by kirby urner May 23, 2017

May 23, 2017

This is officially "the day after" though sprints continue. I've got a looking-back blog post and a Flickr album to share: http://mybizmo.blogspot.com/2017/05/pycon-looking-back.html https://www.flickr.com/photos/kirbyurner/albums/72157681886616111 Great seeing some of you, also former students from OST days.** Kirby ** O'Reilly School of Technology

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updating Wikipedia re partial application in Python
by kirby urner May 14, 2017

May 14, 2017

I document doing so here: http://mybizmo.blogspot.com/2017/05/coffee-shop-networking.html (see link to Wikipedia https://en.wikipedia.org/wiki/Partial_application#Implementations ) At what grade level should we introduce this fragment of lambda calc I wonder? http://mathforum.org/kb/thread.jspa?threadID=2858446 8th grade? The int( ) example in the documentation combines with with developing number sense. Kirby For further viewing: https://youtu.be/eTDH7m4vEiM (re lambda vs delta calc tracks, in Silicon Forest context)

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Decorating a Circle (math + python)
by kirby urner May 11, 2017

May 11, 2017

I'll be among the first to admit, this little Pycon-length talk on @decorators (in a math-learning context) has its weaknesses: https://youtu.be/bQOrmiufSSc?list=PLeBIlkJm4xgnJd1B8AOLIIuclk0ayXlR8 Mainly, I'm "showing my age" (somewhat literally) in that my non-data descriptor, age, doesn't really get into the action the way I claim, given how descriptors without a __set__ rank lower on the MRO totem pole. However, I do wonders with "color". :-D The playlist immediately segues to a San Francisco User Group presentation on the same topic, where Simeon does a better job explaining the rules (MRO). Given my geometric focus, the rest of the videos veer into spatial geometry, wherein I continue to use Python, sometimes Visual Python. Kirby

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Thonny IDE 2.1 released (with pip GUI and plug-in for BBC micro:bit)
by Aivar Annamaa May 3, 2017

May 3, 2017

Hi! I'm happy to announce new version of Thonny, Python IDE for beginners: http://thonny.org/blog/2017/05/02/version_2_1_0.html Eagerly waiting for your feedback! Aivar

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