Mailman 3 July 2017 - 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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MineCraft with Python
by Jurgis Pralgauskis 04 Dec '22

04 Dec '22

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 02 Jul '18

02 Jul '18

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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teaching Python etc.
by kirby urner 25 Jul '17

25 Jul '17

I turned down a $600/day 3 day gig I might not have got anyway, because the textbook goes twelve chapters with no 'class' keyword, and that would define the full complement of our topics. My code of conduct forbids teaching Python that way. The whole point of OOP was here's a way we think in natural language: about Things with properties and behaviors. Maybe some people don't like to be "objectified" and it's true, that can mean something bad, but in the context of the Django ORM, it means an integrated object has the records. The patient, the athlete, the student object, comes with a medical history. Lots of SQL behind the scenes. Rollicking good debate over on math-teach as we exult over the huge numbers turning out to take AP CS.[1] The Learn to Code movement is succeeding, has gained traction. The Coding with Kids that I work for has likewise spread to several more cities, and any successful business model attracts imitators (CwK has a great website for faculty, lets us track everything, including our hours). Is code school the new high school? https://medium.com/@kirbyurner/the-plight-of-high-school-math-teachers-c0fa… (an essay coming up on its first anniversary) The $600/day gig was teaching adults (andragogy vs pedagogy), over the wire, which is how I've been making ends meet. Unfortunately for me, a truck pulled up across the street and started moving wires from pole A (the old one) to pole B (the new one) and wouldn't ya know, my Internet, which goes right through there, cut out. The crew said "not us" (what are the chances?) and took off. CenturyLink is coming tomorrow, but will they have a long enough ladder? I've gotta do my wind-up session 10 of 10 for the Californians. Patrick offered me his office (Comcast). I'm tethered to Internet through my cell phone as I write this (not enough bandwidth for live screen and audio though). We introduce Python classes early because that's the promise of OOP. To sucker for that "ontogeny recapitulates phylogeny" thesis, that we need to slog through a whole semester of procedural programming, before we make a single instance of something, is impossible in practice, at least in Python, as just about everything one touches is an instance of something. This textbook seems to hearken from that era (fortunately receding in the rear view mirror). You'd think in Java at least it'd be classes right out of the gate as one can't but extend a class to get anything done. Python's the same way of course; I think of functions as another type, canned (built-in), with their own syntax, but an instance of the FunctionType nonetheless. Out here in Code School world, the pressure is on to teach Python in two main ways: as a web development language, using projects like Flask and Django, and as a Data Science tool, using pandas, numpy, Jupyter Notebooks and mathplotlib -- but then when it comes to visualization tools, there's a plethora of 2D options. Great talk on this at Pycon2017. I've always been more a 3D guy myself, writing to POV-Ray and later Visual Python. I had a good experience getting vpython over anaconda and embedding same in a Notebook, but that was a while ago. No one pays me for 3D stuff. Maybe we should learn to do stats that way, using more 3D models than we do. Fly through. Not just physics should have all the fun. As it is it seems precious few physics teachers take the "coding a physics engine" approach. Maybe Carnegie Mellon? I'm far from omniscient. Hey, TinkerCAD is loads of fun for simulating an Arduino, a great sandbox if you don't have all the components. I've made some screencasts showing that. [2] The Learn to Code movement is having a big impact, to summarize. Kirby [1] http://mathforum.org/kb/thread.jspa?threadID=2870615 [2] https://youtu.be/AB7fzNK6vjs

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Mathematically Backward States
by Peter Farrell 17 Jul '17

17 Jul '17

> > > You're in California right? A backward state by most accounts. > I'd be offended but everything I've experienced here on the San Francisco peninsula supports your claim. We have a huge STEM and Maker movement but the "M" is only making the odd polyhedron (yes, Kirby they're odd, except for the even ones) or eating pie once a year. My friend's Catholic school is very open to STEM stuff but perhaps only because it's an elementary school. Once the Peninsula kid is in high school the worrying begins and anything that's not on the SATs is seen as suspect. I'm not exaggerating. Another friend of mine was a math teacher, and a fairly traditional, non-techy one at a Catholic high school nearby until this year. He had the audacity to use "non-mathematical language" (he made some joke about "parent" and "child" functions) and he brought in a meat grinder to help the students visualize function input and output. (I play it safe and only draw function machines on the whiteboard.) He lost his job in the middle of the school year, and a student at that school confirmed to me that teachers who explain things in a different way get fired. I jokingly emailed his ex-supervisor and asked about the job. She wrote back with a description that included words like "innovative" and she looked at my webpage (all Python and 3D graphics...) and thinks I should apply for the position! For all she knows, I could be Harry Freaking Potter and cover everything from the Babylonians up to Emmy Noether and still fit in my silly techy stuff. Living in Silicon Valley I thought we'd have a more progressive math curriculum but the techy stuff is only for after-school clubs and summer tech camps. It makes sense, since Americans think we do everything the right way, and especially in such a rich area as Silicon Valley, we're damn near perfect so why change anything? Maybe folks in the Central Valley or beyond are more open minded. Peter Farrell

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Re: [Edu-sig] Edu-sig Digest, Vol 168, Issue 1
by Taz Daughtrey 02 Jul '17

02 Jul '17

I remain puzzled why Monty Python, the actual inspiration of the language's name, isn't more commonly recognized. - Taz > On Jul 2, 2017, at 12:00 PM, edu-sig-request(a)python.org wrote: > > Send Edu-sig mailing list submissions to > edu-sig(a)python.org > > To subscribe or unsubscribe via the World Wide Web, visit > https://mail.python.org/mailman/listinfo/edu-sig > or, via email, send a message with subject or body 'help' to > edu-sig-request(a)python.org > > You can reach the person managing the list at > edu-sig-owner(a)python.org > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Edu-sig digest..." > > > Today's Topics: > > 1. some buried history (kirby urner) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Sat, 1 Jul 2017 15:54:39 -0700 > From: kirby urner <kirby.urner(a)gmail.com> > To: "edu-sig(a)python.org" <edu-sig(a)python.org> > Subject: [Edu-sig] some buried history > Message-ID: > <CAPJgG3RaKmT3i3MTG4fxQ9cbw6t15tApzCpYQHyhCyjVcLk8qA(a)mail.gmail.com> > Content-Type: text/plain; charset="utf-8" > > http://mathforum.org/kb/message.jspa?messageID=10181740 > (link to math-teach) > > This posting to Math Forum mentions > Naga the she-snake (stuffed Python) > mascot representing our Python community > at OSCONs for some years, also Pycons > and Djangocons (though Django had its > own pony). > > Perl may have started the mascot movement > with its camel. > > https://flic.kr/p/a8ackQ > > Kirby >

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some buried history
by kirby urner 01 Jul '17

01 Jul '17

http://mathforum.org/kb/message.jspa?messageID=10181740 (link to math-teach) This posting to Math Forum mentions Naga the she-snake (stuffed Python) mascot representing our Python community at OSCONs for some years, also Pycons and Djangocons (though Django had its own pony). Perl may have started the mascot movement with its camel. https://flic.kr/p/a8ackQ Kirby

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