Chu-chu! clear solution for Max Digit by veky - python coding challenges

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Chu-chu! solution in Clear category for Max Digit by veky

max_digit = lambda number: int(max(str(number)))

March 2, 2020

Comments:

hao.daniel on March 7, 2020, 12:10 p.m.
Glad to see lambda is back again! Thought it's out of favor... these days. ;-)

veky on March 8, 2020, 5:10 a.m.
I was never concerned about what's in favor. >.< But this is an ordinary function train. In every language whose BDFL isn't afraid of high level functions, this would be <pre class='brush: python'>max_digit = compose(int, max, str) </pre> or even (conjugation in APL) <pre class='brush: python'>max under str </pre> (~:

nawalony on Jan. 20, 2021, 1:07 p.m.
I don't get it lambda, can someone explain how it work and when I should use it?

veky on Jan. 20, 2021, 1:37 p.m.
Whenever you write a function of the form <pre class='brush: python'>def name(whatever arguments): return some expression </pre> you can replace its name with `lambda whatever arguments: some expression`.

nawalony on Jan. 21, 2021, 4:59 p.m.
If remember good, I read that lambda have some advantages in compare to normal functions, for example took less memory, is it true? And what about recursion with using lambda, it's open to use it in some way?

veky on Jan. 22, 2021, 11:42 a.m.
The only difference between the two forms above (def vs lambda) is that def knows its own name. Recursion is also possible if you give the lambda a name, or via Y combinator if you're into such stuff. :-) I don't think memory usage is significantly different, besides if you care about memory usage, you really shouldn't be programming in Python in the first place. :-]

myusercb on Feb. 26, 2021, 5:53 p.m.
Lambdas are functions designed to be used on the fly. The difference between lambdas and regular functions is that lambdas don't get assigned a name, they don't have docstrings (can't be documented). It's not a good practice to replace regular functions with lambdas. Good lambda: Note! Used on the fly! ls = [(0,3), (0,2), (0,1)] <h1>Sort by the second element in a tuple</h1> sorted(ls, key = lambda x: x[1]) Bad lambda: Note! Used as regular function <h1>Adds two integers</h1> add = lambda x, y: x + y add(1,2)

veky on Feb. 26, 2021, 6:24 p.m.
Many functions here are of "on the fly" kind. The name is not relevant, it's only an artefact of the CiO testing system. (If you used any of these in the real code, of course you wouldn't give it a name.)

walidshaari on Jan. 23, 2021, 5:47 p.m.
I had an extra step, did not know max can work directly on the string numbers. you can `return int(max(str(number)))`

veky on Jan. 23, 2021, 8:35 p.m.
Even if it didn't, [num for num in blah] is simply list(blah). :-)

marat.m on March 14, 2021, 11:37 p.m.
Very nice use of the lambda. I have yet to author a solution with a lambda and this is a perfect example that will get me going into the right direction.

veky on March 15, 2021, 4:51 a.m.
What you have to do, is write your solution as a simple expression. That's where your creativity should be focused. Once you do that, there's not much difference (for your purposes) between <pre class='brush: python'>function = lambda some argument: expression using that argument </pre> and <pre class='brush: python'>def function(some argument): return expression using that argument </pre>

marat.m on March 15, 2021, 9:31 a.m.
Oh, wow. Thanks again! :)

bkaraica on March 15, 2021, 1:47 p.m.
Yea this is the best way. Thanks

Tylerflx on April 8, 2021, 7:39 a.m.
Your much nicer! This is mine: return max([int(x) for x in str(number)])

veky on April 8, 2021, 6:31 p.m.
Yes, max of ints (of digits) is the same of int of max. :-]

Somebody12345678910_0eb2e11a93 on May 27, 2021, 12:35 p.m.
I really like this solution,...if I would know what max is...

veky on May 27, 2021, 9:34 p.m.
You really should learn to use help. <pre class='brush: python'>>>> help(max) max(iterable, *[, default=obj, key=func]) -> value With a single iterable argument, return its biggest item. The default keyword-only argument specifies an object to return if the provided iterable is empty. </pre>

Somebody12345678910_0eb2e11a93 on May 28, 2021, 6:36 a.m.
Well, where can I use help? In the consol or ... ah maybe I just google it:)

veky on May 28, 2021, 7:07 a.m.
Well, that's also a possibility. But don't you recognize the `>>> ` prompt??

tdazin on July 7, 2021, 1:58 p.m.
Neat and clever! how does max([int(x) for x in str(number)]) compare to this please ?

veky on July 7, 2021, 2:07 p.m.
What comparison do you have in mind? For starters, it's uglier, with an additional pair of parentheses. I wouldn't be surprised if it was slower, too, since it has to make an additional list. A tentative advantage is that it compares the integers instead of digits, but it can also be accomplished above with key=int if you want.

Deadpilot08 on Dec. 17, 2021, 12:50 a.m.
I'm digging this lambda thing, def handy.

ahariti on Dec. 22, 2021, 1:29 p.m.
I see how short it is, it was my first thought, but I do not like this way of solving, there is no algorithmic logic here.

veky on Dec. 22, 2021, 2:13 p.m.
So what, an entity is not an algorithm unless it prickles like a porcupine with loops and assignments? :-D [For a reference to the phrase see <a href="http://www.the-magus.in/Publications/chor.pdf,">http://www.the-magus.in/Publications/chor.pdf,</a> §5.1.1.] Would it be ok if I wrote: <pre class='brush: python'>def max_digit(number): digits = str(number) maxdigit = max(digits) return int(maxdigit) </pre> ?

ss-stalevar on Jan. 1, 2023, 9:05 a.m.
Nice, but I just can't understand, why max function compare 'number' as an int but not as a string? Because that max take a string as an argument (max(str(number)))

veky on Jan. 4, 2023, 4:12 a.m.
Compare it to what? :-) Both max and str have dual personality. max takes either an iterable as a sole argument, or *args as multiple ones. str acts either as a single object (interned in some cases), or as an iterable of its single-character substrings. So max('Veky') is in fact the same as max('V', 'e', 'k', 'y'). Clearer?

ss-stalevar on Jan. 8, 2023, 6:39 a.m.
Thank you for your reply, but still have a question. Here's my point: for example, number == 1234, str(number) == '1234', max(str(number) the same as max('1', '2', '3', '4'), but not the same as max(1, 2, 3, 4). So, in that case, max should compare arguments with their ASCII/UNICODE number, but not the value. Where am I wrong?

ss-stalevar on Jan. 8, 2023, 7:16 a.m.
Oh, I think, I understand. May be it's because ASCII number of 1 < ASCII number of 2 < 3 < 4 etc.?

veky on Jan. 8, 2023, 7:33 a.m.
Yes. BTW it's so funny that ASCII has been obsolete for at least 15 years, yet people still reference it. :-P

ss-stalevar on Jan. 8, 2023, 11:14 a.m.
Well, today I learned a lot of new information))) Thank you!:)

duck1234 on June 12, 2024, 12:42 a.m.
not very clear

veky on June 12, 2024, 4:22 a.m.
What would you find clearer? See <a href="https://py.checkio.org/mission/max-digit/publications/veky/python-3/chu-chu/share/7912472c8aacae39972f8c1d7187e70d/#comment-110299">this comment</a> for example.

TheRealFREDP3D on Oct. 17, 2024, 1:02 a.m.
I get 'lambda' now because of the comments on this solution. Thanks!

Strings and Integers

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