Batteries clear solution for The Greatest Common Divisor by veky - python coding challenges

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Batteries solution in Clear category for The Greatest Common Divisor by veky

import fractions, functools
greatest_common_divisor = lambda *arg: functools.reduce(fractions.gcd, arg, 0)

Aug. 27, 2014

Comments:

stclair.daniel_f70a54fff4764c4 on March 23, 2015, 7:28 a.m.
Well, that's certainly a lot shorter than mine! :)

veky on March 23, 2015, 9:04 a.m.
Considering my reputation here, I guess that's not very surprising. :-)

gmixo on July 3, 2015, 7:14 a.m.
cheater!)

veky on July 3, 2015, 7:41 a.m.
Let's say that the task is to provide a function <pre class='brush: python'>f</pre> that would multiply two numbers. Would you consider <pre class='brush: python'>from operator import mul as f </pre> to be cheating? And why?

gmixo on July 6, 2015, 2:28 a.m.
well actually i assumed that such function already exists, but it take some fun and time to write my own) and at first i felt to waste time but for real it was fun and no regrets) of course you right about any abstract function - we could use it, if it already realised and usage not denied by task

veky on July 6, 2015, 3:40 a.m.
"Write your own" is not absolute, there is a fine graduality of how deep you want to go about replicating Python. (You can go just one level deep and paste the source code for that function, or you can do the same thing with functions in that source code, and so on.) Soon you'll realize that the only two things that make sense is "use batteries" (Python) or "define everything" (Euclid:). And practicality beats purity. ;-) In other view, you can ask about width, not depth, of your implementation---that is, what subset of a language do you allow. You can restrict yourself to just core language, or an intersection of Py2 and Py3, or just those constructs that have direct equivalent in Java:-D, or... whatever. There are practical considerations here: even CiO doesn't allow you to use all stdlib modules. But if something is allowed, it is usually of good enough quality so it's counterproductive to invent the wheel. And of course there is the third consideration: if everybody were importing gcd from fractions, I'd probably write Euclid's algorithm from scratch just to educate people. I have the level that I do here mostly because CiO values diversity, and people like to see an original solution from which they can learn something. Here I guessed that very few people would go this route, and that was the main reason I wrote it this way.

texom512 on July 22, 2015, 9:31 a.m.
"Sparse is better than dense" PEP 0008 And there are several arguments not only one, check your solutions before send them!

veky on July 22, 2015, 3:57 p.m.
... and this is dense - how exactly? IMO, it has exactly the right amount of whitespace, and of token separation. And what's PEP8 got to do with this? Don't worry, this won't go into Python's standard library. :-) Your final sentence shows that your knowledge of Python (and of mathematics) is very sparse. :-P Unfortunately. Please try to learn a bit more about the language before criticizing.

texom512 on July 22, 2015, 4:22 p.m.
First, I stand corrected it wasn't the PEP8, it was the PEP20. "IMO, it has exactly the right amount of whitespace, and of token separation." IMO? I always saw a space between an import and the rest of the code. And to respect a PEP, we must even put two spaces! "Your final sentence shows that your knowledge of Python (and of mathematics) is very sparse." Why??? There are various arguments, I'm right.

veky on July 22, 2015, 4:30 p.m.
Ok, wrong PEP, nevermind. :-) You saw a space, and to follow a (wrong:) PEP, you put two spaces. Whatever. Do you really think that when import is one line, and the "rest of code" is another line, there should be two empty lines between them? Seriously?? <pre class='brush: python'>import ... greatest_... </pre> is more readable to you? I frankly don't believe you. <hr /> Yes, *arg means "various arguments" in Python semantics. (And in math, there wouldn't be much sense in writing GCD of one number - it would just be identity.) What is your problem - that I didn't call it "args"? I'm treating the arg as a single object anyway, it's "vararg tuple" in fact.

texom512 on July 22, 2015, 4:58 p.m.
"is more readable to you? I frankly don’t believe you." OK, maybe not in this example, but a python file rarely contain two lines... "(And in math, there wouldn’t be much sense in writing GCD of one number - it would just be identity.)" I know that, but why do you say it?

texom512 on July 22, 2015, 8:54 p.m.
"You saw a space, and to follow a (wrong:) PEP, you put two spaces." That's not a wrong PEP, it's used in well written libraries like requests: <a href="https://github.com/kennethreitz/requests">https://github.com/kennethreitz/requests</a> That's not enough? You want more proofs? Look here: <a href="https://www.python.org/dev/peps/pep-0008/">https://www.python.org/dev/peps/pep-0008/</a>#blank-lines I quote: "Surround top-level function and class definitions with two blank lines."

veky on July 23, 2015, 9:58 a.m.
<blockquote> OK, maybe not in this example </blockquote> THAT's what I'm telling you. All the time. See the section about "Foolish consistency". Please. And then go and watch Hettinger's "Beyond PEP8". You'll learn much.

texom512 on July 23, 2015, 7:32 p.m.
Where's this section? Thanks for the video, I'm going to watch it ;-). EDIT : But this video recommend the PEP8, it's exactly what I'm doing for you. Sorry, but I'm confused...

veky on July 23, 2015, 10:39 p.m.
I think you might have some problems with concentration. First, the section is right at the beginning. <a href="https://www.python.org/dev/peps/pep-0008/">https://www.python.org/dev/peps/pep-0008/</a>#a-foolish-consistency-is-the-hobgoblin-of-little-minds And second, are you sure you watched the whole video? You're missing a gorilla. ;-P

veky on July 29, 2016, 5:01 p.m.
Are you really, seriously thinking that the same considerations should apply to <pre class='brush: python'>requests</pre>, an enormously widely used library behemoth of 4.5 thousand commits developed over 5 years, and a solution to a CiO task, written in 3 minutes, that cannot be imported anywhere and has exactly 2 lines of code? If there ever was a foolish consistency... :-o I must say I simply cannot believe you can be so misdirected here. Also, it's fascinating that you chose the smallest possible program (in number of lines) where your objection could be "applicable". So I'm going with the theory that you're just a sophisticated troll. Sorry.

ddavidse on Dec. 14, 2020, 11:14 p.m.
I just think it's wrong to import gcd when the whole exercise is to compute the gcd. You basically skipped the exercise and went straight to the answer.

veky on Dec. 15, 2020, 5:41 a.m.
I have already had that discussion, above. Did you read it? Do you have anything to add?

ddavidse on Dec. 15, 2020, 11:32 a.m.
I read it and no, I don't have anything to add. I just wanted to give a reason for downvoting your solution because it seemed a bit unfair to downvote and say nothing.

veky on Dec. 15, 2020, 11:48 a.m.
Well, to me it seems unfair to downvote even with your arguments. :-) But ok, of course you have the right to downvote anything you want. :-]

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