Key clear solution for The Most Wanted Letter by veky - python coding challenges

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Key solution in Clear category for The Most Wanted Letter by veky

from string import ascii_lowercase as letters
checkio = lambda text: max(letters, key=text.lower().count)

Jan. 4, 2015

Comments:

springulum on Jan. 19, 2015, 12:27 a.m.
holy crap this is short

veky on Jan. 19, 2015, 9:30 a.m.
You ain't seen nothing yet, I dare say. ;-)

jcook00 on Feb. 5, 2015, 9:46 p.m.
solutions like this seem less complex than the longer ones. but, it requires knowing things about the language that many beginners just don't know. researching lambda now...

veky on Feb. 5, 2015, 11:19 p.m.
Beginners don't know many things. And more importantly, different things (Many beginners told me "lambdas are easy, but oh my, those list comprehensions..." - or some other thing). The purpose is to learn the language, not to solve the tasks, obviously. :-) About lambda: wherever you see `lambda args: expr`, you can replace it with `f` (new name), where in the same scope before it you have <pre class='brush: python'>def f(args): return expr </pre> And that's it. `lambda` is reducible to `def`. `def` is strictly more complicated than `lambda`. If you understand `def`, you understand `lambda`. The only problem is, you have to really understand `def`. ;-)

koykomesto on Jan. 19, 2023, 8:41 p.m.
The claim here, I would say, is not about the solution itself, but about tagging it as "Clear solution" - beginners don't know many things and come here to learn, but the learning journey starts with basic constructions and algorithms. As a beginner, you learn how to implement algorithms with basic language constructions, then learn alternative ways (like comprehensions), then libraries, etc. 3 of 4 "best" solutions for this particular exercise use the same construction ( max( ... , key = string.count) ), 2 of 3 use lambda notation. Most (if not all) of the "Best Creative" solutions on this island are lambda one liners. Do you think that using lambda notation brings creativity? Seems strange to me...

veky on Jan. 19, 2023, 10:12 p.m.
You would be right if there was a universally agreed-upon set of "basic constructions and algorithms". Just a few minutes of talk with other beginners (especially if they come from different cultural background than you) shows that this is hopelessly naive. Even here on CiO, which is just one community, there are beginners that find comprehensions totally obvious, but don't grok lambda, and vice versa. Try to understand, what you call "basic" and "alternative" are just your views, they are not universal. And they usually depend on the languages you were previously exposed to. If 3 of 4, or 2 of 3, best solutions use some construct, one obvious hypothesis is that it actually is the best way to do something. Instead of clinging to your subjective ideas of what is (not) basic [please note that this solution uses neither comprehensions nor libraries], maybe it would be a more profitable idea to actually try to see how these solutions work. The worst that can happen is that you learn something. :-] Lambda is usually completely irrelevant, same as def would be irrelevant in most tasks if it were used. It is just a scaffolding, a way to tell CiO "here is the solution". In most normal everyday code, you wouldn't use neither lambda nor def for it, you'd just write your expressions inline.

frbls on April 13, 2015, 4:27 p.m.
Is there any guarantee that max returns the first element in case of tie?

veky on April 13, 2015, 6:23 p.m.
Of course. <a href="https://docs.python.org/3.4/library/functions.html?highlight=max">https://docs.python.org/3.4/library/functions.html?highlight=max</a>#max If multiple items are maximal, the function returns the first one encountered.

frbls on April 15, 2015, 9:29 a.m.
Oh, that is good to know. It looks like in was implementation defined until python 3.

veky on April 15, 2015, 9:34 a.m.
Horrible. :-o Well, one more reason to use the True Python. ;-)

Czarinov on Aug. 15, 2015, 7:59 p.m.
Damn you, Veky! This is even shorter than I expected from you! So, does Max returns the right letter because of already ordered ascii?

veky on Aug. 15, 2015, 10:36 p.m.
You ain't seen nothing yet. :-P Yes, ascii_lowercase is ordered naturally (by ord, in this case).

rajsharmabannu on May 24, 2015, 4:16 p.m.
this is too good.

veky on May 24, 2015, 5:54 p.m.
You've yet to see many things. :-)

anuj74 on June 24, 2015, 4:21 p.m.
why u always use lambda. see the program of one who is in the first rank.

kest_iv on Aug. 13, 2015, 4:36 p.m.
everytime i check your answers my mind == blown! such a creative approach you have. For how long do you code? Any tips on what books to buy/read? Which web resourses to check?

veky on Aug. 13, 2015, 7:26 p.m.
Thank you. :-) I code for almost 30 years now - tried many languages, was good in many of them, but not like this. Python really suits my mind. [So if you want to be a wizard, it's probably better to find a language that suits your mind, instead of imitating me.:] I'm not really a book person - books IMO become obsolete too easily in this quick civilization - though I do read a lot, and have (kinda) photographic memory, which really helps :-). Web? docs.python.org. It's all there. :-D Though, for cultural immersion, it helps to follow mailing lists: python-ideas (if you're crazy enough) and python-dev (if you're smart enough). ;-]

kest_iv on Aug. 14, 2015, 8:34 a.m.
thank you for reply ;]

wbkoetsier on Jan. 25, 2016, 2:22 p.m.
yeah... slowly getting lambda now... thanks for sharing this solution.

veky on Jan. 25, 2016, 3:39 p.m.
Np. Glad you learned something. BTW the concept of bound methods is much more important lesson here than lambda. ;-) [Especially since it can be used to avoid an unnecessary lambda.;]

wbkoetsier on Feb. 1, 2016, 9:35 a.m.
eeehhhhmmm... bound/unbound methods. The bound method is bound to an instance of a class. The unbound methoud is not bound to an instance, only to the class. I saw many examples using 'class A' with some method f, and then they call it like a = A() and a.f and such. These examples just make me more confused. Would you give me an example of when you would use one or the other? In language, not in code. Maybe explain what about your lambda is bound method (the lambda itself? The max function?). I'm really not seeing it at the moment :( ps <a href="https://docs.python.org/2/tutorial/classes.html">https://docs.python.org/2/tutorial/classes.html</a> gave me some pointers, as did <a href="https://docs.python.org/2/library/stdtypes.html?highlight=unbound">https://docs.python.org/2/library/stdtypes.html?highlight=unbound</a>#methods but all those online blogs and tutorials just made me more confused...

veky on March 3, 2016, 10:51 a.m.
I don't know how I managed to miss this. :-/ Hope you'll still see the answer. First, when trying to grasp language concepts, please refer to Py3 documentation, not Py2. The documentation is clearer, but more importantly, the language itself is clearer and has fewer basic concepts. It's always better to learn something new on Py3, and then only if you're curious or you need to, see what are the differences on Py2. Case in point: Py3 has only one kind of classes, and bound methods work the same for all of them. Py2 has two kinds, "classic" and "modern" classes, which are irreducible one to another, and have slightly different notions of bound methods. Also, Py2 has the notion of unbound method as a separate object - in Py3, "unbound method" is just an ordinary function. And so on. Since you want me to use (natural) language rather than code, I'll use circumlocution to answer your question. :-P In my code, neither the `lambda` (called `checkio`) nor `max` are bound methods. Bound methods are what you get when you access the attribute on an instance, which on the class is an ordinary function. So, if `A.f` is a function, and `isinstance(a, A)`, (usually) `a.f` is a bound method. What's the difference between `A.f` and `a.f`? They are both callable, but they (usually) differ in the number of arguments they are callable with. If `A.f` is a function accepting three arguments (`self`, `x` and `y`), then `a.f` is callable with two arguments, named `x` and `y`. In the body of `f`, the name `self` refers to `a` itself. So, we can say <pre class='brush: python'>a.f(3, 5) <~~~> A.f(a, 3, 5) </pre> This has many benefits, but the one I use here is cheap specialization. That `f` above probably does something with `self`, with `x` and with `y`, but there are many cases when what it does with `self` is common to many invocations. In other words, it's called many times with the same `self`, while `x` and `y` vary. In this concrete example, the `key` parameter to `max` is a function. It counts how many times a letter appears in text (lowered, but let's ignore that for now). We can write <pre class='brush: python'>str.count(text, 'a'), str.count(text, 'b'), str.count(text, 'c'), ... </pre> but in fact all of these use the same first argument, while second argument is the one that `key` function is expecting. We can write <pre class='brush: python'>, key=lambda x: str.count(text, letter) </pre> but in fact bound methods give us a much easier way. Since `str.count(text, letter)` is the same as `text.count(letter)`, we have a perfectly fine callable thing to set `key` to. Simply <pre class='brush: python'>key=text.count </pre> Clearer?

Vincent_Fan on April 5, 2016, 4:11 p.m.
very cool

veky on April 5, 2016, 10:04 p.m.
Thanks.

drdiz on July 18, 2017, 11:19 a.m.
I am looser s=list('abcdefghijklmnopqrstuvwxyz') def checkio(text): max=0 min=40 nr=text.lower() for i in range (0,len(s)): x=nr.count(s[i]) if x>max: max=x min=i return s[min] print(checkio("Lorem ipsum dolor sit amet"))

Yan.zilla on Aug. 8, 2017, 7:42 p.m.
Damn, nice solution!

veky on Aug. 8, 2017, 8:18 p.m.
Why "damn"? :-)

Yan.zilla on Aug. 8, 2017, 10:20 p.m.
Cuz it took me twelve lines!

veky on Aug. 9, 2017, 7:56 a.m.
Ah... if it's any consolation, I've seen ratios of 1:100, or even more. This is not so bad. :-D

jonnytang6 on Oct. 29, 2017, 2:09 p.m.
cool

Nep on Nov. 4, 2017, 9:13 a.m.
Nice! I didn't know about string.ascii_lowercase and about a key in max and min. It can be useful :-) But the same :-) <a href="https://py.checkio.org/mission/most-wanted-letter/publications/bryukh/python-3/max-count/">https://py.checkio.org/mission/most-wanted-letter/publications/bryukh/python-3/max-count/</a>

Nep on Nov. 4, 2017, 9:24 a.m.
My solution: <a href="https://py.checkio.org/mission/most-wanted-letter/publications/Nep/python-3/short/">https://py.checkio.org/mission/most-wanted-letter/publications/Nep/python-3/short/</a>

veky on Nov. 4, 2017, 9:31 a.m.
Yes, it seems that there is just one obvious way to do it. :-D Still, I like mine better. It doesn't pointlessly rebind text, just counts in the lowered one.

veky on Nov. 4, 2017, 9:34 a.m.
Weird... it says that I have to solve the mission first. Since you posted this link in the comment to my solution of that mission, I'd say there's a bug here somewhere. @oduvan?

Nep on Nov. 4, 2017, 10:45 a.m.
It's not a bug. I created a classroom and made a mistake in settings :-) Maybe now it works :-)

Nep on Nov. 4, 2017, 11:49 a.m.
Sorry. It was my mistake. Now it works.

jkopp on Jan. 5, 2018, 4:18 a.m.
short and cool~ maybe you can use just 1 line :)

veky on Jan. 5, 2018, 5:42 a.m.
Of course I can, but why would I do that? Contrary to popular opinion, it's not my intention to golf everything. I'm just writing at a natural abstraction level. It's not my fault that many tasks here are so simple their natural solution is only one line long. :-P

Torben on March 5, 2018, 9:51 p.m.
This looks elegant. When I look at my solution it looks like Frankenstein, ugly, but it works. To my defense I am both a programming and python beginner, so there is hope ;) I really should get a deeper understanding of that lambda function and how to use it.

veky on March 6, 2018, 11:19 a.m.
As I said above, beginners usually mystify lambda, and often without a good reason. Here is the same solution without lambda: <pre class='brush: python'>from string import ascii_lowercase as letters def checkio(text): return max(letters, key=text.lower().count) </pre> It's really not so different. :-)

Grunwalski on March 26, 2018, 11:51 a.m.
Why is the lambda used here, to avoid defining a function ?

veky on March 26, 2018, 12:43 p.m.
I do define a function. <pre class='brush: python'>>>> import types >>> isinstance(checkio, types.FunctionType) True </pre> Only I don't do it using statements, but using expressions. Which is good enough for this case, since the function is reducible to `max` builtin. :-)

Duomim on Sept. 21, 2018, 1:06 p.m.
我学习了两个月Python了,解答了半天,看到你的代码,人和人的差距咋这么大

Duomim on Sept. 21, 2018, 1:07 p.m.
不好意思,只会中文,也不知道作者能看懂不,哇哈哈

veky on Sept. 22, 2018, 3:45 p.m.
Google Translate is pretty good these days. :-) Thank you.

Duomim on Oct. 4, 2018, 1:24 p.m.
啊哈哈,谢谢回答,还是第一次和外国人说话呢,虽然是通过这种留言的方式. 才开始学习编程2个月,很好玩,有机会再请教你! 我一直用google,吐槽下中国的"baidu",广告太多了

veky on Oct. 4, 2018, 6:04 p.m.
No problem. Feel free to ask whenever you have problems. :-)

Duomim on Oct. 19, 2018, 11:32 a.m.
哦.那太好了,但是我不知道怎么联系你,在中国访问国外的网站会非常卡顿,也许我应该发邮件给你,但不确定你能不能收到,中国是一个神奇的地方,会有一些奇怪的限制.

veky on Oct. 19, 2018, 11:51 a.m.
Just ask here, why would you send me an email? :-)

johnAndOrange on May 1, 2019, 12:25 a.m.
seeing your answer to the fellow of my country,i think that you are so kind and friendly :) thanks for your solution.

veky on May 1, 2019, 2:03 a.m.
As I said, Google Translate is the real hero here. :-)

pumacens_64305eb2e37c43308c6c7 on Oct. 22, 2018, 5:27 a.m.
i can't belive this, why i can't make code like this :,v. The road is still too long :,v

veky on Oct. 22, 2018, 7:02 a.m.
Of course it's long. You don't want to traverse it too quickly. ;-D

yowee on Dec. 5, 2018, 1:19 p.m.
concise!! So Cool!

the.maryam.sadeghi on March 17, 2019, 12:02 p.m.
For a moment my eyes were scrolling down when I realized the code is finished long ago :))))

veky on March 17, 2019, 3:26 p.m.
Prepare to be surprised. There are much shorter codes of mine here on CiO. ;-)

roman.alilov on Sept. 4, 2019, 2:44 p.m.
Like your solutions, because they made me search out and learn new libraries suited for needed type of variables.

bsquare on Sept. 18, 2019, 10:24 a.m.
Quick, clear, and perfect. Usually a way to learn from you. Thanks for your solution!

jsg-inet on July 13, 2021, 10:56 a.m.
Cool and smart!

viktor.chyrkin on Oct. 23, 2021, 2:50 p.m.
good job on key=text.lower().count. I learned something new.

Strings and Integers

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