Mailman 3 April 2022 - 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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snapshot 2022: data structures and algorithms
by kirby urner 28 Apr '22

28 Apr '22

In a few minutes I'll join Sunshine Elite Education online and help out like a gym coach in some ways, because Algorithms and Data Structures, at the 8th grade level, is a doorway into a competitive sport: competitive programming (CP). Although the contests are geared towards youth, say high school level, in full adulthood comes the "coding interview" and so the same skills apply. Then later tonight, I'll be marching a small army of the the future through the numpy + pandas + matplotlib ecosystem. I'd call that Algorithms and Data Structures too, in the numpy's ndarray and the DataFrame are both data structures. With lots of algorithms to go with. My new Hello, World page: https://nbviewer.org/github/4dsolutions/clarusway_data_analysis/blob/main/K… My way of merging both worlds is to tackle the "longest increasing sequence in a matrix" problem, a coding interview classic, with numpy. I'm sure that would not be acceptable in the contest area, but it's a way of merging my two worlds. If you want to see more, click on USAOS in the Notebook allow and scroll to where I'm developing those algorithms (Kadane's Algorithm etc.): Eureka Moments. https://nbviewer.org/github/4dsolutions/elite_school/blob/master/Exercises.… I think of this as anthropology, me some guy in the field. Kirby

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Fwd: exhibit: after class note to students, Silicon Forest elite school
by kirby urner 21 Apr '22

21 Apr '22

---------- Forwarded message --------- From: kirby urner <kirby.urner(a)gmail.com> Date: Wednesday, April 20, 2022 at 7:50:48 PM UTC-7 Subject: Re: exhibit: after class note to students, Silicon Forest elite school To: Trimtab Book Club <trimtab-book-club(a)googlegroups.com> A very similar letter to my recent one, why? I'm teaching two groups, this one entirely online. So what I test out with one group, I adjust for the next, leap frog fashion. I think it's worth sharing them both, to promote a stereoscopic view of the terrain. ======================== Thanks for tuning in to our biweekly "radio show" (like talk radio, but with pictures). Today our theme was algorithm speed, which is described using O-notation. "Polynomial time" O(n^2) for example, is only able to process about 5000 data elements in a second, rougly speaking. That's an approximation I cited from the USACO PDF I want you to have: https://usaco.guide/CPH.pdf That 300 page PDF has a healthy dose of what we call Discrete Math. It's what you will need to do well in CP (competitive programming). Sorting, finding shortest paths through a graph, or solving a subarray problem ("Kedanes algorithm" is part of the lore), have all been implemented for you. The USACO documentation counsels against trying to reinvent the wheel on the fly i.e. reinventing the best known algorithms. Rather, your job is to know which algorithm is called for, and then to make use of the relevant library, e.g. for sorting. My talk zoomed back, away from CP, to show more of the terrain: algorithms as used in the movie and simulations industries, data structures as tiles from a globe. I demonstrated a real time rendering of tensegrity structures, implemented by a world leader in the field, Gerald de Jong. Thanks to WebAssembly generated from Rust, your browser is able to show his creations involving in real time, not as a pre-recorded movie. Sometimes it's hard to tell the difference. https://pretenst.com/app/#construction;Triped https://pretenst.com/app/#construction;Halo-by-Crane Real materials (not CGI): https://pretenst.com/construct ion/2021/07/27/brass-bubble-120 <https://pretenst.com/construction/2021/07/27/brass-bubble-120> This is all still Algorithms and Data Structures. I ended with kennethsnelson.net. That's not the website I built for him, and for which he gave me Barrel Tower (showed on screen), but the one that came after, when he found the right paid professional. I was just doing it as a friend. Kenneth, an Oregonian (born and raised in Pendleton), was in inspiration for both Gerald and myself. Lastly, what some of you may of missed as I shared this early (as a loose end from last time): https://youtu.be/gFEE3w7F0ww Lex Fridman is a great interviewer and in this case his guest is a member of the Python community who has a lot to do with the tools I've been introducing (e.g. numpy and Anaconda). Kirby *Course Name*: Data Structure and Alg orithms in Python *Datetime*: 01/29-06/19 Wednesday,Sunday 6:00pm-7:00pm *Location*: Online10 Thanks, Sunshine Elite Education

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update re Algorithms and Data Structures (pre college)
by kirby urner 21 Apr '22

21 Apr '22

What I didn't fully realize, when I signed on as the Algorithms and Data Structures teacher, for two groups of 8th graders, is that ADS is pretty much the property of CPers at the age level. CPers? Competitive Programmers. They join olympiads <https://nbviewer.org/github/4dsolutions/elite_school/blob/master/Exercises.…> , which present them with problems needing those special algorithms. There's a premium placed on speed, both to come up with a solution, to implement it, and to have it run at optimal speed. As the old guy applications programmer with a philosophy background (Princeton), I'm not a past champion. Nor have I had to go through a gauntlet of job interviews for coding jobs with big companies, and that's where CPers look next. Sure, maybe these olympiads are mostly for a younger crowd, but the ability to choose the right algorithm quickly is what will get them a job at the end of the day. That's the PR, which I'm just passing along. My initial approach was somewhat overlapping but different. I was more thinking in terms of *Mathematics* *for the Digital Age* and other discrete math tomes we have talked about at length in this archives. Working backwards from RSA (the public key algorithm), I know we want to cover Fermat's Little Theorem and Euler's generalization featuring totients and totatives. So what are those? Let's do some Group Theory while we're at it and show how the totatives of N, multiplied modulo N, form a finite group. Fibonaccis, generating primes, things of that nature <https://nbviewer.org/github/4dsolutions/elite_school/blob/master/ADS_intro_…> . Then, in a more innovative mode, I've worked to expand data structures to include "structured data" such as json, html, xml, csv i.e. serialization protocols. In addition, I've sought to bring in DataFrames from the array based computing world of data analysis. Numpy and pandas. I think for many in a high school setting, what will serve them going forward is good old Anaconda and all that implies. As a base of operations. As a main productivity tool. Jupyter Notebooks rock, in my opinion. What I'm attempting, in microcosm, is to make Algorithms and Data Structures useful to non-CPers as well, i.e. those not especially interested in or drawn to competitive programming. It's not like algorithms and data structures should go off their radar as a consequence. The last innovation I'm trying involves keeping things more right brain i.e. graphical not just lexical. A graph, or network, is already a visually accessible data structure. It's almost a no-brainer to then bring polyhedra into the picture, as more graphs, with edges and nodes. Polyhedra also need to be stored and retrieved somehow, i.e. back to structured data and SQL. Indeed, in other writings I advocate introducing polyhedrons as paradigm objects, when learning OO, as they're both abstract mathematical and colorful tangible. They have attributes. They come with methods (scale, rotate, translate...). Where do we go from polyhedra? To divided (tiled) spheres and global data. To world maps <https://nbviewer.org/github/4dsolutions/elite_school/blob/master/ADS_sandbo…>. More data structures. More algorithms. I started a new sandbox intending to import global data tiles, but that ended up corrupting my old Mac Pro. Anaconda snuck in some incompatible upgrades. So far, I only have one "sandbox" <https://nbviewer.org/github/4dsolutions/elite_school/blob/master/ADS_sandbo…> devoted purely to polyhedrons in the ADS portion of my repo (much more elsewhere), a table of relative volumes built with pandas. The volumes won't seem familiar and the relevance of this table is not widely echoed in other literature, except in the matrix of suppressed American philosophy. One of our leading futurists, from the 1960s through the early 1980s, made a big deal out of the tetrahedron and its ability to serve as a basis for our relative volume concept. Even a tetrahedron of edges one could have volume one, in his recasting. This is a topic I've posted about extensively here on edu-sig over the years, and on Math Forum, although the latter was purged of its public discussion groups, breaking lots of links. My attitude is I want to be one of those teachers who took the Bucky Fuller stuff seriously enough to want to include it in downstream published open source works. You'll see if you go to bfi.org/synergetics that my Github writings <https://nbviewer.org/github/4dsolutions/DigitalMathematics/blob/master/Mart…> are currently on tap to give scholars some exposure to the philosophy in question. Part of walking my talk is to showcase said material in a workaday context, namely in an 8th grade level Algorithms and Data Structures class. Kirby

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a curriculum dev in the Silicon Forest
by kirby urner 03 Apr '22

03 Apr '22

I'm continuing to develop curriculum for a tiny elite college prep school smack in the center of the Silicon Forest, a place called Bethany Village, which specializes in offering after school elective time activities (e.g. martial arts, foreign language learning). [0] Nearby: Intel, Tektronix, ESI... [1] The Sunshine Elite School runs both after school enrichment and for-credit day school programs. I call myself "a developer" or even a "dev", but if people ask what I develop, I say "curriculum". I teach four times a week and look for ways to include student work in ways they permit. The school already has a Hall of Fame for competitive tournament winners. Doing a stellar project around Wordle or Chess would be another way to develop one's portfolio, through lasting links in the text itself. I wonder what other educators here think of the following proposition: === Most of the wood pulp published Algorithms and Data Structures (ADS) textbooks inherit from a day before "array based computing" and therefore have no "DataFrame" to integrate. Not as such. Of course they have 2D arrays (Python: lists of lists), i.e. row and column data, but not anything as sophisticated as a DataFrame in R or pandas. So let's include the DataFrame in a next iteration of ADS! That's certainly what I'm doing.[2] That puts machine learning algorithms within the reach of a pre-college student. We needn't dive deep into deep learning. We're free to dabble. We're still young and carefree (student attitude). "Buckle down data science" comes later, for those who so choose. === I see Jupyter Notebooks (Colab, Kaggle Notebooks etc.) as an extension of the desktop publishing revolution of the 1980s (PageMaker + Apple LaserWritier == professional quality publications). I remember working with nonprofits and NGOs and those days (at a place called CUE), and how excited these organizations were to be able to upgrade the look and feel of their literature. The web itself held a similar promise: the little guys wouldn't be trounced by the big guys, just because the big guys were big. Jupyter Notebooks, with embedded videos and data visualizations etc., put more of a level playing field under all would-be publishers. Our content is potentially as high quality as the content in professional papers and magazines. As long as we study our Tufte... Look how Jake VanderPlas goes back and forth between Notebooks and a wood pulp (non-interactive, yet standard setting) O'Reilly book. [3] As a curriculum dev, I'm able to bypass the wood pulp publishers entirely, using open source tools to create open source assets available to fellow faculty. To me, this looks like a quiet revolution against the hegemony of "those with enough money to dress up" (i.e. make their stuff look pro). Kirby Cc: Wwwanders (Silicon Forest, Doug Strain affiliate) Citations: [0] https://flic.kr/s/aHBqjzJdXN [1] https://www.oregonencyclopedia.org/articles/silicon_forest/ (mentions Doug Strain) [2] https://nbviewer.org/github/4dsolutions/elite_school/blob/master/ADS_sandbo… [3] https://github.com/jakevdp/PythonDataScienceHandbook

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