Si, comprehendo! clear solution for Sum Numbers by veky - python coding challenges

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Si, comprehendo! solution in Clear category for Sum Numbers by veky

sum_numbers = lambda text: sum(int(word) for word in text.split() if word.isdigit())

March 6, 2020

Comments:

igharok on March 31, 2020, 3:28 p.m.
The same way as mine

Swatik_Rulezz on April 16, 2020, 8:33 a.m.
i did't know .isdigit() until now :) Thank you for your solution :)

piter239 on April 21, 2020, 7:08 a.m.
lambda rules!

veky on April 21, 2020, 7:40 a.m.
Comprehension rules here. Lambda just gives it an opportunity to shine. :-)

piter239 on April 21, 2020, 7:50 a.m.
well, I used comprehension myself, but doing it in lambda was a nice thing to add

veky on April 21, 2020, 7:54 a.m.
What you used is not comprehension. (See another solution of mine, it's appropriately called "no comprehendo".;) And you misuse docstrings.

piter239 on April 21, 2020, 8:01 a.m.
you are right, it was mapping. So many new things to try out and find the right place to use and not to use. How do I learn about the best way of using docstrings?

veky on April 21, 2020, 8:14 a.m.
You can start with PEP257. It is a bit dated, but contain lots of advice. For this particular instance, it's very simple. Docstrings aren't for implementation notes. Comments do that (though in this case, they are completely superfluous, of course). Docstrings should explain how to call your function, what do the arguments mean, and what you'll get in return. Possibly exceptions, corner cases, examples or the time (complexity class) used. In short, docstrings are for users of your function. Comments are meant for maintainers of it. Not the same thing at all.

piter239 on April 21, 2020, 8:24 a.m.
ok, got it! In the moment I have to explain thing to myself in order to remember it the other day)) Thanks for your time and attitude!

veky on April 21, 2020, 8:39 a.m.
Not just explain, but use. (<a href="https://english.stackexchange.com/questions/226886/origin-of-i-hear-and-i-forget-i-see-and-i-remember-i-do-and-i-understand)">https://english.stackexchange.com/questions/226886/origin-of-i-hear-and-i-forget-i-see-and-i-remember-i-do-and-i-understand)</a> I honestly think that the reason people mix comments and docstrings (and misuse both) is simply that they've almost never written code complicated enough to need either. :-)

piter239 on April 21, 2020, 10:51 a.m.
good point! I have to agree, there is a pretty wide gap between code I could write easily and code which actually would need comments. My present situation is - I studied CS til 1998, and then never actually wrote something meaningful after 1999. And I have to decide - start now or just let it be for this incarnation? ))

veky on April 21, 2020, 10:53 p.m.
Whatever your religious or philosophical convictions are, surely you don't believe that CS knowledge survives reincarnation? :-] Even if it did, do you think it will be relevant 50 years from now? :-P

piter239 on April 22, 2020, 10:01 a.m.
there are quite amusing variants of reincarnation belief systems out there )) But no, the incarnation part surely was meant as a joke ))

seajinkim89 on June 7, 2020, 9:45 a.m.
Thank you for your solution!

PypperPerri on July 14, 2020, 8:23 p.m.
I took a week just to copy the solution from someone else probably you. I tried to find a way to convert the string to an int in the hopes that would spit out some numbers. meanwhile I only heard about isdigit() after I seen the solution. it all makes sense but in the end I didn't find it out myself which is very depressing

veky on July 15, 2020, 4:33 a.m.
Hm. May I ask what is the purpose of this comment? Do you wish some tips about what you could have done differently to "find it out yourself"? And what does it mean "to copy the solution"? You're not supposed to see others' solutions before you solve the mission yourself.

veky on Dec. 5, 2022, 3:51 a.m.
And the fact that this comment has -2 means that someone other than @PypperPerri didn't like it. May I ask why?

mohammad.moaddi on Aug. 25, 2020, 8:03 a.m.
isdigit() works on a whole string not only on chars! Nice to know!

veky on Aug. 25, 2020, 9:09 a.m.
There are no chars in Python as a separate type. Same as there are no digits as a separate type. There are just one-digit integers. And one-character strings. :-)

mohammad.moaddi on Aug. 25, 2020, 11:23 a.m.
Ahaa Nice

veky on Aug. 25, 2020, 11:43 a.m.
The analogy is deeper than it seems at first glance. In value-semantical static languages such as C, the primitive types are the ones that fit in a box of fixed size ("word" of a processor, usually 64 bits). So string cannot be a primitive, so arrays are used. But int can be a primitive, since people writing in C usually don't care for numbers greater than 9,223,372,036,854,775,807. :-) Also, float can be a primitive, since we've learned to live with the fact that 0.1 + 0.2 != 0.3. :-P But Python's ints are mathematically exact, and as such, they aren't fixed-size anyway. Python2 had a single "cell" fitting in a word as a separate type, but Guido realized it made no sense and removed the distinction in Py3K.

dhbarnett on Oct. 14, 2020, 7:20 p.m.
This won't work if there are any negative numbers

veky on Oct. 14, 2020, 8:40 p.m.
Correct. But I interpreted "numbers" in the precondition as "digits" (since everything else are single chars), so I think dashes should be added in the case they seriously wanted to include the possibility of negative numbers.

KazAndr on Dec. 29, 2020, 7:27 a.m.
Nice solution!

midkager007 on Feb. 1, 2021, 1:23 p.m.
Good

Juntian_Deng on March 9, 2021, 9:21 p.m.
what is lambda?

veky on March 10, 2021, 3:15 a.m.
It is a way of defining functions as expressions. It says: to `sum_numbers`, take `text` and calculate `sum(int(word) for word in text.split() if word.isdigit())`. Converting expressions to statements, it can be written as <pre class='brush: python'>def sum_numbers(text): return sum(int(word) for word in text.split() if word.isdigit()) </pre>

juanj.azpiroz on March 14, 2021, 11:56 a.m.
I beg you to clarify my doubt, because If I print sum_numbers as shown in yr solution what is printed is "function <lambda> at 0x7fcc12ca7f28". But if I delete "lambda text" it prints correctly the integers sum within text. Many thanks

veky on March 15, 2021, 4:49 a.m.
That's exactly what I'm talking about when people pester me about my lambdas: it's just an artefact of CiO checking system. Of course, if in the real life you have some `text` and want to print the sum of all the "numbers" (natural) from it, you'd do exactly that: <pre class='brush: python'>print(sum(int(word) for word in text.split() if word.isdigit())) </pre> But for various reasons, CiO wants a function that will be called with `text` as an argument. So in fact instead of <pre class='brush: python'>print(sum_numbers) </pre> you should <pre class='brush: python'>print(sum_numbers(text)) </pre> But yes, it's roundabout, only because CiO can more easily test a function than an expression.

juanj.azpiroz on March 20, 2021, 11:08 a.m.
Many thanks for yr interesting and clear explanations

uxban on March 30, 2021, 5:26 a.m.
откуда вы беретесь такие блин

veky on March 30, 2021, 10:33 a.m.
It's a literal translation of the task text: sum all the words from text that look like numbers (converting them to numbers in the process). :-)

CIOHarazi on April 28, 2021, 8:21 a.m.
Just want to say you're a top act. I not only learn from your solutions but also from your replies to anyone who has a question. Thank you!

CIOHarazi on April 28, 2021, 8:25 a.m.
Would you use isnumeric() or isdecimal() for this solution instead of isdigit() or is there a specific reason you chose that particular function? Thanks

veky on May 4, 2021, 11:19 a.m.
Honestly, I used isdigit since it is shortest :-D, and in the context of the task (The text consists from numbers, spaces and english letters) it doesn't matter which you use. But (as always), Unicode is complicated. :-] The "whole truth" is <a href="https://stackoverflow.com/questions/44891070/whats-the-difference-between-str-isdigit-isnumeric-and-isdecimal-in-python">here</a>, but TLDR is roughly: decimal implies digit implies numeric, but neither converse implication holds. some digits that aren't decimal (digits by themselves, but not composable into numbers): <pre class='brush: python'>፩፪፫፬፭፮፯፰፱᧚ ⁰¹²³⁴⁵⁶⁷⁸⁹₀₁₂₃₄₅₆₇₈₉ ①⑵⒊⓸❺➅➐🄉𐩀𐩁𐩂𐩃 𑁒𑁓𑁔𑁕𑁖𑁗𑁘𑁙𑁚 </pre> some numerics that aren't digits (signify numeric values, but not as sequences of digits): <pre class='brush: python'>⅐ ⅑ ⅒ ⅓ ⅔ ⅕ ⅖ ⅗ ⅘ ⅙ ⅚ ⅛ ⅜ ⅝ ⅞ ⅟ ¼ ½ ¾ ৴ ৵ ৶ ৷ ৸ ৹ ୲ ୳ ୴ ୵ ୶ ୷ ௰ ௱ ௲ ౸ ౹ ౺ ౻ ౼ ౽ ౾ ൘ ൙ ൚ ൛ ൜ ൝ ൞ ൰ ൱ ൲ ൳ ൴ ൵ ൶ ൷ ൸ ༪ ༫ ༬ ༭ ༮ ༯ ༰ ༱ ༲ ༳፲ ፳ ፴ ፵ ፶ ፷ ፸ ፹ ፺ ፻ ፼ ᛮ ᛯ ᛰ ៰ ៱ ៲ ៳ ៴ ៵ ៶ ៷ ៸ ៹ Ⅰ Ⅱ Ⅲ Ⅳ Ⅴ Ⅵ Ⅶ Ⅷ Ⅸ Ⅹ Ⅺ Ⅻ Ⅼ Ⅽ Ⅾ Ⅿ ⅰ ⅱ ⅲ ⅳ ⅴ ⅵ ⅶ ⅷ ⅸ ⅹ ⅺ ⅻ ⅼ ⅽ ⅾ ⅿ ↀ ↁ ↂ ↅ ↆ ↇ ↈ ↉ ⑩ ⑪ ⑫ ⑬ ⑭ ⑮ ⑯ ⑰ ⑱ ⑲ ⑳ ㉑㉒㉓㉔㉕㉖㉗㉘㉙㉚㉛㉜㉝㉞㉟㊱㊲㊳㊴㊵㊶㊷㊸㊹㊺㊻㊼㊽㊾㊿ ⑽ ⑾ ⑿ ⒀ ⒁ ⒂ ⒃ ⒄ ⒅ ⒆ ⒇ ⒑ ⒒ ⒓ ⒔ ⒕ ⒖ ⒗ ⒘ ⒙ ⒚ ⒛ ⓫ ⓬ ⓭ ⓮ ⓯ ⓰ ⓱ ⓲ ⓳ ⓴ ⓾ ❿ ➉ ➓ ⳽ 〇〡〢〣〤〥〦〧〨〩〸〹〺㆒㆓㆔㆕㈠㈡㈢㈣㈤㈥㈦㈧㈨㈩㊀㊁㊂㊃㊄㊅㊆㊇㊈㊉㉈㉉㉊㉋㉌㉍㉎㉏㐅㒃㠪㭍一七万三九二五亖亿什仟仨伍佰億兆兩八六十千卄卅卌叁参參叄四壱壹幺廾廿弌弍弎弐拾捌柒漆玖百肆萬貮貳贰阡陆陌陸零 </pre> In short, I think the most in spirit of this mission would be to use `isdecimal`, since they are the only ones with which `int` can work.

FrozenCandy on May 14, 2021, 7:59 p.m.
Gr8

veky on May 15, 2021, 3:52 a.m.
xe1

veky on Dec. 21, 2021, 3:37 a.m.
Comeon, nobody got this? :-D 2e1 is ten twos. So, xe1 is ten x, that is, thanks. :-)

mu_py on Jan. 9, 2023, 9:50 a.m.
<pre class='brush: python'>2e1 is ten twos </pre> sorry, I don't get it. could some1 pls explain?

veky on Jan. 9, 2023, 11:59 a.m.
Python can explain. Type 2e1 into its prompt. ;-) <a href="https://python-reference.readthedocs.io/en/latest/docs/float/scientific.html">https://python-reference.readthedocs.io/en/latest/docs/float/scientific.html</a> If you have any more questions, feel free to ask.

mu_py on Jan. 9, 2023, 1:32 p.m.
xxxx

mu_py on Jan. 9, 2023, 1:33 p.m.
xxxx

veky on Jan. 14, 2023, 2:59 p.m.
That's just 40% of xe1. ;-DD

hecronk on June 29, 2021, 1:14 p.m.
Very good, dude

gamer995 on July 19, 2021, 3:16 p.m.
great job!

Selindian on Feb. 23, 2022, 11:10 p.m.
Thank you. Your solution has showed me how lambda and compression could be used. This is still relatively new for me.

veky on Feb. 24, 2022, 5:24 a.m.
In real world, do use comprehension [not compression;], but don't use lambda this way. Lambda is just an artefact of this system (CheckiO), in ordinary coding you simply say <pre class='brush: python'>text = ... get it or calculate it somehow sum_numbers = sum(int(word) for word in text.split() if word.isdigit()) ... somehow use sum_numbers </pre> That is, it's just one link in the chain of processing that you do.

Selindian on Feb. 24, 2022, 10:31 a.m.
Thank you for the clarification. That is exactly what I meant. I have used the compression without lambda to see how it works and afterwards with lambda (as replacement for the original function). So I hopefully understand both a little bit better now. :-)

veky on July 30, 2023, 11:51 p.m.
Yes, though you really shouldn't confuse comprehension with compression. ;]

ALukashevich on April 22, 2022, 6:27 a.m.
Thanks!

veky on April 22, 2022, 12:39 p.m.
You're welcome. :-)

sarahsorlien on Jan. 5, 2023, 3:53 p.m.
Two courses in Python and I never "got" lambda til now. Thanks

veky on Jan. 5, 2023, 6:56 p.m.
Every idiot and their dog thinks they know how to make a Python course, and beginners are usually not in a position to adequately judge which ones are good. CiO is infinitely better. ;-)

veky on Jan. 6, 2023, 3:47 a.m.
... and so we've gone a full circle. People who for more than 10 years couldn't stand my solutions with lambdas, now like a comment from (& my answer to) a person who finally understood lambdas precisely because of my solutions. And that's the beauty of CiO. You don't have to like somebody's style to understand that it can be very helpful to others. In fact, CiO is like a ten thousand of those silly Python courses :-D rolled into one, where an user can pick and choose what makes sense to them.

dig on March 8, 2023, 11:28 p.m.
Could the "if" statement go before the "for"?

veky on March 9, 2023, 9:08 a.m.
The main problem with your question is that these are not statements. :-) But anyhow, if you wrote <pre class='brush: python'>sum_numbers = lambda text: sum(int(word) if word.isdigit() for word in text.split()) </pre> Python would complain about not having an else. Because it would think you intended to wrote a conditional expression (int(word) if word.isdigit() else something) instead of a comprehension.

dig on March 9, 2023, 10:28 a.m.
Ah I understand. Could I write "else pass" to fix it I guess. But you are right, like this is much simple. thanks :)

veky on March 9, 2023, 3:19 p.m.
No, because again, these are not statements. :-P pass is a statement.

Ali.Pxl on July 2, 2023, 1:45 a.m.
.split() & .isdigit() are saviors

veky on July 2, 2023, 4:08 a.m.
Saviors of what, Python's reputation of a expressive language? :-) To me, the real hero here is the generator comprehension.

Ali.Pxl on July 3, 2023, 7:31 a.m.
came from java to python, don't blame me :), great one-line code btw

veky on July 3, 2023, 10:10 a.m.
As I said, Java also has both of these (though isDigit has to be mapped over, since Java believes in char as a separate type). But the thing that enables me to write this elegantly is a comprehension.

lbe on Aug. 3, 2023, 1:40 p.m.
short and efficient !

zezyaka on Sept. 12, 2023, 10:16 p.m.
Good Job, Mate!

veky on Sept. 13, 2023, 5:46 p.m.
At least it's not a checkmate. :-]

ottoottoottoottoottoottootto on Oct. 4, 2023, 6:59 a.m.
This is crazy solution, appreciate!

veky on Oct. 4, 2023, 12:49 p.m.
Not as crazy as your username. :-]

dududu8778 on Jan. 28, 2024, 11 a.m.
Hi veky Thank you for sharing your solutions. They are very clear and helpful to learn how to code in python.

TheRealFREDP3D on Oct. 17, 2024, 10:17 p.m.
Thanks for taking the time to answer and share your knowledge. The interactions below your solutions are a goldmine of good information. It's better than most books and courses.

veky on Oct. 18, 2024, 1:05 a.m.
I'm glad it helps you. I always say there are many ways to learn Python, and this one is helpful for lots of "storytelling apes". ;)

Strings and Integers

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