Mailman 3 April 2004 - Edu-sig

Re: [Tutor] what? (late nite entertainment) (*)
by Gregor Lingl 24 Mar '05

24 Mar '05

Now: early morning corrections ... Alfred Milgrom wrote: > Hi Gregor: > > Hard to work out what is what :) as there seems to be a typo in one > line of your code: > > if x[z]: x[z*z:n:z]=y[z*z:n:z] > > (At least it doesn't work on my machine with Python 2.2) > Yeah, I had the idea when playing around with some new features of Python 2.3, as I do sometimes late at night - before shutting down my computer. This one I found at: http://www.python.org/doc/2.3.3/whatsnew/section-slices.html and I looked for an example for use of "assignment with extended slices" ... > Also the subroutine breaks for n = 1 or less. > Maybe you need a line at the start to say > if n <2 : return [0] > what() was intended to generate all primes less than n. (In fact it's an implementation of the sieve of Eratosthenes). The bugs came not only from not beeing interested in primes less than 2 ;-) but also from beeing a little tired already. Sorry. I think the following version repairs that - and hopefully uses less obfuscating variable names (which in fact originally was part of the "riddle"): def primes(n): sieve, zeros = range(n), [0]*n sieve[:2]= 0,0 i = 1 while i*i < n: if sieve[i]: sieve[i*i:n:i]=zeros[i*i:n:i] i += 1 return [p for p in sieve if p] Regards, Gregor >

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Re: How do we tell truths that might hurt
by Daniel Ajoy 02 May '04

02 May '04

From: Anna Ravenscroft <anna(a)aleax.it> > > In other realms, the path to be able to do something actually useful is > > much longer. > > The path isn't that long and is far likelier to keep their interest. > > Teaching folks that almost any repetitive task involving text, dates, or > numbers can be automated by writing a simple program is more likely to get > them excited about programming than teaching them that you can add 2+ 2 or > solve quadratic equations... I agree with Anna. Common tedious tasks that people regularly do are: * Matching "similar" names in two different lists (say 200 names in each list) * Finding the difference of two lists of names, the intersection. * Making tables out of lists (changing the structure of a data set) * Generating repetitive texts, or graphics, with little variations. Knowing a little programming could help them. The following is a random sentence generator program (I don't find it harder than "technical/scientific computations"): to rand.sentence output (sentence noun.phrase verb.phrase) end to noun.phrase output (sentence "the adjective noun) end to verb.phrase output (sentence verb noun.phrase) end to adjective output pick [red blue green big small fat skinny loud quiet] end to noun output pick [computer elephant boy girl aardvark] end to verb output pick [likes eats visits hates paints] end ---- ? print rand.sentence the red boy visits the blue elephant ? print rand.sentence the quiet aardvark eats the quiet computer ? print rand.sentence the red computer likes the red elephant ? print rand.sentence the big aardvark likes the skinny elephant Here is a link to a "poetry generator" and other programs in the "Language Arts" section in MicroWorlds Logo: http://www.microworlds.com/library/languagearts/ Daniel

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Mathematical Patterns in African American Hairstyles
by Jason Cunliffe 29 Apr '04

29 Apr '04

http://www.math.buffalo.edu/mad/special/gilmer-gloria_HAIRSTYLES.html

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RE: [Edu-sig] Talking Stat Blues
by Arthur 27 Apr '04

27 Apr '04

Jason writes - >I can't take it any more. I really need your help please.. >In these painfully contorted times, media are forever saturating news >reports with the latest polls just in. >53% think yes leader x is lying scum >46% said no he's not, he's got Dog on his side >1% undecided >etc >If you are very lucky they specify the size of the sample. 1000 people >perhaps. >But they never speak it. Instead we get all this nonsense >"Most Martians said ....." >"The majority ...." >etc >I need your help to find a [new] more honest, preferably Pythonic and >revealing way to speak about these numbers. Jason, you sure expect a lot of Python. But as it happens, I understand that Python 2.4 will include a statistics module. But I think you will find it to be part of the problem, rather than part of the solution. As I am assuming it implements and makes available the functionality that allows one to draw conclusions, for a large population, within a defined margin of error, from a small sample. It seems to me the study of such a module would lead you to conclude, with me, that the distortions you sense may exist in such polls are in the words, not the numbers. Art

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Talking Stat Blues
by Jason Cunliffe 26 Apr '04

26 Apr '04

I can't take it any more. I really need your help please.. In these painfully contorted times, media are forever saturating news reports with the latest polls just in. 53% think yes leader x is lying scum 46% said no he's not, he's got Dog on his side 1% undecided etc If you are very lucky they specify the size of the sample. 1000 people perhaps. But they never speak it. Instead we get all this nonsense "Most Martians said ....." "The majority ...." etc I need your help to find a [new] more honest, preferably Pythonic and revealing way to speak about these numbers. Let's assume a population of 300,000,000 And a sample of 1000 53% yay 46 % nay 1% dohnuts My teacher vigorously taught us whenever we saw any % signs to **always** ask out loud "Percentage of What ?" So when I see/hear any polls or statistics, I get pretty crazy because I immediately look for the size of the sample and then ask: "How on this earth can they presume to multiply that tiny sampling from 1000 to 300,000,000 ?" And then I wonder " Why on this earth do other people go along with this madness?" It must be something to do with how they were taught to read and speak basic math. And since we are all here praying for the days when programming is an integral part of our basic literacy, I want to hear your best suggestions about how we can prevent such nonsense in the future. Spoken dialogue with Python examples please. thank you very much -- Jason

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RE: [Edu-sig] How do we tell truths that might hurt
by Christian Mascher 26 Apr '04

26 Apr '04

Thanks Arthur, this was a way of telling _a_ truth, without hurting anyone. I think I never really laughed out loud before when reading Edu-Sig (serious postings most of the time). I really enjoyed this! Christian Arthur Siegel wrote: > Date: Fri, 23 Apr 2004 05:28:48 -0500 > From: Arthur <ajsiegel(a)optonline.net> > Subject: RE: [Edu-sig] How do we tell truths that might hurt > To: hancock(a)anansispaceworks.com, edu-sig(a)python.org > Message-ID: <0HWM00MEKD3WA9(a)mta9.srv.hcvlny.cv.net> > Content-Type: text/plain; charset=us-ascii > > Terry - > >>import re, string >> >>illegal_re = re.compile(r'[^a-zA-Z\s]+') > > > Huh? > > >>words = [w for w in illegal_re.sub(' ', open('myfile', >>'r').read()).lower().split() if len(w)>2] > > > Whoa? > > >>Now that wasn't terribly difficult, was it? ;-) > > > Piece of cake! > > Art

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Our universe
by Arthur 26 Apr '04

26 Apr '04

I just came across this, for the first time: "An exciting new course for students in all Disciplines:" http://www.wa.gov.au/perthobs/OurUniverse/PDFs/Poster.pdf The demonstration programs are in Python, using VPython. Thrilled to find that PyGeo (as a minor player) is also a required download for the curriculum: http://www.wa.gov.au/perthobs/OurUniverse/software.html Art

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How do we tell truths that might hurt
by ajsiegel＠optonline.net 26 Apr '04

26 Apr '04

To me the most significant aphorism from Dijkstra's essay: "How do we tell truths that might hurt?" at: http://www.cs.virginia.edu/~evans/cs655/readings/ewd498.html is the second: """ The easiest machine applications are the technical/scientific computations. """ In advocating math/science explorations as the focus in introductory level programming education it might well sound like one in advocating some kind of ideologoical sense of rigour over a more gentle and humane approach to the subject of programming. But if one accepts that: The easiest machine applications are the technical/scientific computations. one is simple advocating starting at the beginning. And demonstrating and elucidating and empowering folks to handle the easy before one attempts to ask them or expect them to approach the more difficult. And for those that go no further, they will have learned to do some actually useful things, in a programming language.. In other realms, the path to be able to do something actually useful is much longer. Yes, a Literature student might be enticed to know that programming could be made useful in finding semantic patterns in the works of Joyce. The problem is that its hard. Much harder than using numeric and geometric concepts as a jumping off point. I, for one, never expect to understand how to compile a pattern using the re module. (if I even stated that lack of understanding correctly). Art

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Linuxfest and iPython
by Jeff Sandys 23 Apr '04

23 Apr '04

Thanks, Kirby, for giving your presentation at Linuxfest. One thing Kirby mentioned in his post that I found real interesting is how to slowly build a class in IDLE. I would use a notepad, cut and paste each modified class. What Kirby did is store the class with each instance: class Q: def __init__(self): self.Q = Q.__class__ then is later versions he would use self.Q instead of Q to create the new objects: class Qv1(Q): def method(self): return self.Q() Of course I am leaving a lot of stuff out here, see his slides for the example. The other thing that Kirby mentioned is that high school students should be able to understand the RSA algorithm. Until last year I would have thought that was extreme, but then I read, _In Code: A young woman's Mathematical Journey_ by Sarah Flannery. This is a wonderful book for anyone interested in math. The book is divided into three parts; the first part is her childhood experiences of the math puzzles that her father would put up on the caulk board in their kitchen, then she discusses modulus math, the RSA algorithm and another encryption algorithm she helped develop as a summer intern, the third part is her journey as the winner of the Ireland young scientist contest and the following contests and presentations around the world. The book has a clear and understandable explanation of the RSA algorithm along with the Mathematica code she used. The book should be an inspiration to all, especially to young women with an inclination to math, who would rather be playing "football" and ride horses, as the author, high schooler Sarah Flannery, would. Thanks, Jeff Sandys ________________________________________________________________ The best thing to hit the Internet in years - Juno SpeedBand! Surf the Web up to FIVE TIMES FASTER! Only $14.95/ month - visit www.juno.com to sign up today!

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Re: [Edu-sig] Reuters.com -- College Science Classes Are a Bore
by ajsiegel＠optonline.net 23 Apr '04

23 Apr '04

> The real problem is that no one wants to pay for the materials to > make it > happen. And of course there is the opposite problem. Getting the academic world to believe that materials - in the case of Python representing how many person-days of effort??? - might not *need* to be paid for. And can yet be taken eminently seriously. Getting the check approved is part of the "certification" process. No checks, no certification. I am willing to volunteer - again, for the cause - to be the designated recipient of checks from any institution that finds the process unavoidable. ;) Art

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