Obvious creative solution for Monkey Typing by veky - python coding challenges

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Obvious solution in Creative category for Monkey Typing by veky

count_words=lambda t,W:sum(w in t.lower()for w in W)

Aug. 6, 2014

Comments:

smjefferson602 on Sept. 28, 2014, 9:59 p.m.
Another learning moment for me!! ty

veky on Sept. 28, 2014, 10:24 p.m.
I'm glad to help. ;-) If you meant summing the bools, read about Iverson bracket once you have a lot of free time. Powerful stuff. ;-)

lena-py on Aug. 4, 2015, 3:58 a.m.
Yes, summing the bools was a cool concept but the exciting learning experience for me was in breaking apart the lambda and discovering generators!

smjefferson602 on Sept. 28, 2014, 10:19 p.m.
A question if you choose to accept it: My first solution to Monkey Typing looked like the code below. When it was checked by the "weird" latin text string, my code came back with 2 for "sum" and "anything" when only sum was in string(correct answer being 1). What caused this? It was a mess of unnecessary statements but I want to learn from it. ty def count_words(text, words): text = text.lower() words = list(words) for i in words: if i not in text: words.remove(i) words = set(words) num = int(len(words)) return num count_words("Lorem ipsum dolor sit amet, consectetuer adipiscing elit.", {"sum", "hamlet", "infinity", "anything"})

veky on Sept. 28, 2014, 11:06 p.m.
First, when you write code block in comment, indent it by 4 spaces. This is really hard to read. You're lucky that I knew what your problem was even before I saw the code. :-D Golden rule: never remove elements from a sequence you're iterating through. lists are sequential in memory, and when you iterate through [1,2,3,4] and iterator is at 2, you remove 1 and the list gets shifted back in memory, so next iterator is at 4: you've skipped 3. You see what happened? <pre class='brush: python'>1 2 3 4 ^ 1 2 3 4 ^ 2 3 4 ^ </pre> If you really want to do something like this, iterate through a copy: "for i in words.copy():". No, Python doesn't automatically copy things for you - that way lies value semantics, const&, and much gnashing of teeth. ;-) That being said, all these "conversions" are really unnecessary: <pre class='brush: python'>def count_words(text, words): for word in words.copy(): if word not in text.lower(): words.remove(word) return len(words) </pre>

smjefferson602 on Sept. 28, 2014, 11:28 p.m.
Sorry, whitespace must have been removed while copy/paste of code. Thanks for the iteration knowledge! Never thought of removal that way.

veky on Sept. 29, 2014, 7:30 a.m.
Now I think I know why you had converted words to a list. When it was a set, the above code you wrote raised RuntimeError("set changed size during iteration"). So you just swept it under the carpet with list(words), right? ;-) set is smarter: it keeps a hashtable of entries, so it's usually obvious if size has been changed. list is much dumber (closer to the representation) structure, and checking len would be an extra step, so Python doesn't do that. But it's still wrong to remove elements from list being iterated through.

numenor96_a1a2b7b06d624327a506 on Feb. 6, 2015, 7:35 p.m.
<a href="http://www.checkio.org/mission/monkey-typing/publications/numenor96/python-3/first/?ordering=newest">http://www.checkio.org/mission/monkey-typing/publications/numenor96/python-3/first/?ordering=newest</a>

veky on Feb. 6, 2015, 9:21 p.m.
This is the place to put the link, yes. ;-)

iggymas on July 7, 2015, 9:14 a.m.
It's to hard for understanding, disloice!

veky on July 7, 2015, 10:24 a.m.
Your comment is too. :-) Seriously, do you want to understand it? That can probably be arranged.

AMJ on Aug. 8, 2015, 3:05 p.m.
good and clear!

veky on Aug. 8, 2015, 5:54 p.m.
Thanks. :-) But if I put it in the "Clear" category, no doubt many would shout at me. :-D

Moises.py on July 22, 2016, 1:50 a.m.
veky you are awesome

veky on July 23, 2016, 5:17 a.m.
Thank you. :-D

vlad.bezden on July 20, 2017, 1:24 a.m.
I really like your solution. The only problem I see with it is that t.lower() called every time for each w in W.

veky on July 20, 2017, 4:44 a.m.
That was raised already. So I wrote <a href="https://py.checkio.org/mission/monkey-typing/publications/veky/python-3/dunder-map-lambda-oh-my/">another</a> solution. ;-)

Strawberry on Nov. 13, 2017, 1:30 p.m.
how about len(list(filter(lambda ws: ws in words.lower(),text)))

veky on Nov. 13, 2017, 4:41 p.m.
What how about? How simpler can it be? :-D <pre class='brush: python'>list(filter(lambda w: condition, text)) ~~~> [w for w in text if condition] </pre> Also, why construct a list just to take len of it? Just sum the conditions.

StefanPochmann on Nov. 13, 2017, 6:37 p.m.
Recently I saw someone seriously suggesting `list(map(lambda x: print(x), someiterable))` to print some iterable's elements. In a StackOverflow <a href="https://stackoverflow.com/revisions/47123701/1">answer</a>, i.e., specifically to show people how to do it.

veky on Nov. 14, 2017, 5:20 a.m.
I saw many people seriously suggesting many things. I even saw the president of the United States of America seriously suggesting building a wall on the border to Mexico. :-Q Even if you want to do it that way (not to mention `print(*someiterable)`:-P), you can still write it in a less ugly way: `[print(x) for x in someiterable]`. But of course, there really is no gain from writing an expression with sideeffects, when an equally long statement is available. <pre class='brush: python'>for x in someiterable: print(x) </pre>

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