First clear solution for House Password by Renelvon - python coding challenges

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First solution in Clear category for House Password by Renelvon

checkio = lambda s: not(
        len(s) < 10
        or s.isdigit()
        or s.isalpha()
        or s.islower()
        or s.isupper()
    ) 

#These "asserts" using only for self-checking and not necessary for auto-testing
if __name__ == '__main__':
    assert checkio('A1213pokl') == False, "1st example"
    assert checkio('bAse730onE4') == True, "2nd example"
    assert checkio('asasasasasasasaas') == False, "3rd example"
    assert checkio('QWERTYqwerty') == False, "4th example"
    assert checkio('123456123456') == False, "5th example"
    assert checkio('QwErTy911poqqqq') == True, "6th example"

Feb. 13, 2014

Comments:

bryukh on Feb. 17, 2014, 9:17 a.m.
This is original and interesting solution, but is not "Clear" for newbies. I would give you thumbsUp if it was in a different category.

Denis_Gerashchenko on Jan. 5, 2019, 2:16 p.m.
You look like Max Payne XD

romazhuzha on Feb. 18, 2014, 12:28 a.m.
This way it would be one of the most clearer, I suppose: <pre class='brush: python'>def checkio(data): try: data[9] except IndexError: return False return not (data.isdigit() or data.isalpha() or data.islower() or data.isupper()) </pre>

Hanna_Hofman on Oct. 15, 2014, 8:14 a.m.
I've read recently about exceptions, and found that catching them is rather expensive, so it's better to use them only when you assume that exception won't be thrown in most cases. And I don't think that catching an exception is clearer that checking data length via len(data).

zds2 on April 10, 2014, 12:02 p.m.
It has the same problem on '##########' string as the solution of the topic-starter.

Reb_Sadran on March 10, 2014, 8:23 p.m.
Awesome, thanks for posting! really clever approach.

zaulan on Aug. 24, 2015, 9:37 a.m.
Exceptions are not for program logic, only for error handling.

penn201500 on May 27, 2016, 12:11 p.m.
really clever and clear solution, tks!

schroedingersbells on Sept. 3, 2017, 5:33 p.m.
Love this. Catching exceptions is expensive in other languages, like C, not in python. In line with the 'Forgiveness not Permission' paradigm, pythonistas use Try-Except heavily for logic and flow control, not just exceptions.

DanielDou on Feb. 22, 2014, 8:02 a.m.
This is very clever code. :) Gave you a thumbs up! But the flaw in it seems you can bypass those conditions and get True if you just use symbols and ignore all the other conditions. For example: checkio("#$%%#%#%#%#%") == True checkio("$$$$$$$$$$$") == True checkio("$$$$$$$$$$7") == True It will not check for numbers or letters in such case.

Renelvon on Feb. 22, 2014, 2:34 p.m.
Indeed! I need to filter symbols out before applying the test, but I need to reintroduce them when checking for length. So, a correct solution along the same lines is (I hope): <pre class='brush: python'>def checkio(s): fs = ''.join(filter(str.isalnum, s)) # keep only letters and digits return ( len(fs) >= 1 # There is at least one letter or digit and len(s) >= 10 # ... and there are at least 10 characters and not fs.isalpha() # ... and there is at least one digit and not fs.isdigit() # ... and there is at least one letter and not fs.islower() # ... and not all letters are lowercase and not fs.isupper() # ... and not all letters are uppercase ) </pre> Thank you for the review!

maurice.makaay on Oct. 27, 2014, 11:57 p.m.
The story says: "The password contains only ASCII latin letters or digits." From that I derived that special characters like punctuation would have to be counted as invalid.

Renelvon on Dec. 1, 2014, 9:57 p.m.
You are absolutely right! Nevertheless, redoing the solution to count for punctuation was a nice exercise. :)

alexander.gorelyshev on April 30, 2018, 5:54 p.m.
Besides, it's more readable now, since we are neither negating the whole returned expression, nor using slightly confusing lambda syntax. Thumbs up!

DanielDou on Feb. 24, 2014, 4:47 a.m.
No problem. :)

Kup9_NpS on July 28, 2015, 5:18 p.m.
I dont really understand this) Where i can read about it properly?

mu_py on Oct. 30, 2022, 8:53 p.m.
The comments in your rewritten code helped me to understand 👌 I wasn't aware that `isupper()` and `islower()` only check letters and kindly ignore any digits...

Strawberry on Nov. 13, 2017, 8:38 a.m.
Greate review, thumbs up for you!

LSC on Jan. 27, 2018, 6:13 a.m.
Thank you for the review!, But i thank the "len(fs)" should be greater than or equal three.Because after filter there is least one lowercase, as well as digit and uppercase.

endomorphism1 on March 2, 2014, 4:48 a.m.
Great Solution. I learned a lot.

Reb_Sadran on March 10, 2014, 8:29 p.m.
Thanks, made me research lambda, now I got it. It definitely looks cleaner and more readable this way. Though I would prefer functions in the long run.

kidcobain on April 2, 2014, 8:40 a.m.
i dont really understand this. if you use islower() outside of that function it checks if all characters are lower and it drops false if not,all character need to be lower to drop true. but inside of that function it drop true with only 1 character lower in the string can anybody explain this to me ?

oduvan on April 3, 2014, 12:04 p.m.
<blockquote> but inside of that function it drop true with only 1 character lower in the string can anybody explain this to me ? </blockquote> Why do you think so?

kidcobain on April 3, 2014, 12:19 p.m.
maybe i dont made my point clear.. my english is poor. this line drops false 'bAse730onE4'.isdigit() <h1>=> False</h1> i think it does because all characters has to be digits to be true but in the function checkio = lambda s: not( len(s) < 10 or s.isdigit() checkio('bAse730onE4') #=> True isdigit() drops true, i think that, it checks character by character, its that right? why is that?

Reb_Sadran on April 3, 2014, 12:25 p.m.
isdigit() drops false, but we are using not in front of the whole thing, so what he basically does is checks if the password string is not all numbers or all letters or all uppercase or all lower case. Then he uses not on the final result, so if everything is false he gets true.

Rocketich on Sept. 26, 2017, 4:57 p.m.
If one of the rules are true(password is weak), then we will get true everywhere. Because of "or" We change result to false with "not" . <pre class='brush: python'>len(s) < 10 checks length . We need it to be false . s.isdigit() checks only digits . We need it false . Because we also have letters(upper and lower) . s.isalpha() checks only lettes (any . lowercase and uppercase) . We need it false because we have digits . s.islower() checks lower . s.isupper() checks upper . </pre>

normsome on May 9, 2014, 1:58 a.m.
Neat trick, but not particularly clear or easy to read.

badbird on May 9, 2014, 5:38 a.m.
if the password is '+++++++++++',it also return True, but it is a wrong answer.

BranoZarnovican on June 13, 2014, 2:11 p.m.
Not correct (as pointed out by others). Someone should update the solution check to filter this. And not very readable as well..

Renelvon on June 19, 2014, 9:33 a.m.
I agree it is not correct (for a correct solution, see my code snippet in the comments). I disagree it is not readable; all it does is check none of the "bad cases" occur. It is as declarative as a (short) solution can be.

vagner on June 21, 2014, 10:30 a.m.
Good solution, but assert checkio('wry911poqqqq') == True, "7th example" isn't correct for example:)

taserian on July 7, 2014, 4:48 p.m.
It's a good solution, but I wouldn't call it clear.

luis.vianapodesta on July 14, 2014, 9:33 p.m.
Comenting this code can easier to understand: <ul> <li>if one of the conditions are True, lambda s: will return not(True) = False</li> <li>if the password have less than 10 characteres -> Return false</li> <li>if all the characteres are digit or all characteres are alphanumeric -> Return false</li> </ul> <h1>At this point, only passwords mixed with numbers and letters with 10 or more char. pass True</h1> <ul> <li>islower and isupper receive both False only if the alphanumeric are mixed in lowercase and uppercase</li> <li>The password "++++++++++++" gets True, but it isn't on the Precondition...</li> </ul> <blockquote> Precondition: re.match("[a-zA-Z0-9]+", password) </blockquote>

bit.man on July 22, 2014, 2:49 a.m.
Nice work. These string methods make it simple.

clockkent on July 27, 2014, 10:59 p.m.
I thought the intention of this example was to use regular expressions versus avoiding them. This is an excellent example of not using regular expressions.

dsnyder0cnn on Aug. 30, 2014, 5:22 p.m.
I've seen references to "lamda" in Python docs, but this is the first example that I've seen. I'm not completely sure that I understand yet, but this gives me some inspiration to ready more.

Renelvon on Dec. 1, 2014, 10:01 p.m.
The lambda here is purely for style; I could have written the same code using a casual function.

mydaemon on Oct. 1, 2014, 11:48 p.m.
Smart usage of lambdas, but it's wrong since does not obey one of the requirements: the characters in the password must be ascii. This requirement can not be met with your code, you should use a second lambda that would traverse the string looking for any non-ascii code.

Renelvon on Dec. 1, 2014, 10:04 p.m.
The "Precondition" clearly states that all I should expect in the string are letters and digits. This means I don't have to do any extra checking. However, should that check be my duty, I would do it with <pre class='brush: python'>s.isalnum() </pre>

texom512 on Nov. 9, 2014, 11:44 a.m.
It's not clear!

Renelvon on Dec. 1, 2014, 10:40 p.m.
The lambda may be confusing you; perhaps it would be clearer without it. What else is there that is not clear? De Morgan's laws? The Python Library? I wrote this solution trying to stay as close as possible to the task specification; I lay out a number of bad cases and ensure none of them happens. Perhaps you were expecting a for loop or a bunch of regular expressions. None of that is needed. Programming is not about for loops; programming is about clearly articulated intention. This is what this solution provides.

jgo3000 on March 22, 2015, 9:17 a.m.
I am a super noob (can I use terminology like that at age 41?), but I just wanted to say that this is the second time in a few days that I have been inspired by your code. The main problem I had to solve when figuring this one out was how to check if at least one character in the string was upper or lower or whatever, and so like many others, I set up boolean variables and set them to True once the condition was met. It never occurred to me to "do the opposite" and check if the conditions were not true! Of course! Thank you for helping me see outside of the box!

shavy69 on Feb. 13, 2015, 7:03 a.m.
Clever approach

antropod on March 9, 2015, 10:51 p.m.
This solution is so unclear

p42es on Sept. 14, 2015, 10:57 a.m.
Try to check regular expressions, it's so much clearer ;)

HalEuphrates on March 22, 2015, 10:49 a.m.
I don't like this lambda joker, it prevents learners from learning. An approach that shows what the logic/reasoning behind the steps would be a better approach. Something like romazhuzha's approach below I guess.

Hernando on April 2, 2015, 2:27 p.m.
Good, but lambdas function is not readable for noobs, I think The way of Simplest clear for newbies would be some like: <pre class='brush: python'>def checkio(data): digito = "" alfa = "" mayus = "" minus = "" if len(data) >= 10: for x in data: if x.isdigit(): digito = "bien" if x.isalpha(): alfa = "bien" if x.isupper(): mayus = "bien" if x.islower(): minus = "bien" return digito == "bien" and alfa == "bien" and mayus == "bien" and minus == "bien" </pre> Thanks for your solution, is nice.

HaiLu on April 21, 2015, 7:27 p.m.
The solution is not robust and very error-prone

rajsharmabannu on May 24, 2015, 1:04 p.m.
nice one! :)

andrey.pashkin on Aug. 30, 2015, 12:42 a.m.
But the requirement "The password contains only ASCII latin letters or digits" does not work here. For example, I have got "True" for this password: "1,2,3,4,5 - Вышел Зайка Погулять".

p42es on Sept. 14, 2015, 11:03 a.m.
Oh, man, don't be noob... read the comments above. The password ALREADY contains only ASCII latin letters or digits. It's what you receive as Input.

mike.seagul on Oct. 9, 2015, 3:38 p.m.
gg

audrey_sean on Jan. 13, 2016, 4:27 a.m.
Can someone explain why the following expression evaluates to True? Is the number 2 treated as a lowercase letter? <pre class='brush: python'>>>> '2a'.islower() True </pre>

rgpatch on Jan. 26, 2016, 12:35 p.m.
As a newbie, I'm wondering if it matters that the isalpha function deals with the Unicode character set, while the problem specifies that the password must be in the ASCII character set. The Python library says isalpha "Return true if all characters in the string are alphabetic and there is at least one character, false otherwise. Alphabetic characters are those characters defined in the Unicode character database as “Letter”, i.e., those with general category property being one of “Lm”, “Lt”, “Lu”, “Ll”, or “Lo”. Note that this is different from the “Alphabetic” property defined in the Unicode Standard." Won't the solution allow the password to include non-alphabetic characters that are in the Unicode character database as “Letter”?.

hernandezj on Jan. 29, 2016, 2:19 p.m.
Pretty slick solution!!!

sbccdx007 on March 20, 2016, 1:43 p.m.
checkio('*^%!!!!!!!!!!') return True

saharnasiri71 on March 27, 2016, 9:18 a.m.
It wasn't clear for me, what is "lambda" and why do you write not(...?

wuhuarui1992 on April 27, 2016, 9:15 p.m.
cool not or

NCoder on May 13, 2016, 6:51 a.m.
This made me look up lambda: a quick way to make one-line functions

penn201500 on May 27, 2016, 12:10 p.m.
awesome and creative solution!

Thenbacker on Oct. 23, 2016, 12:49 a.m.
Nice use of lambda!

k.shogo on April 27, 2017, 10:02 p.m.
its great!

LOACH on Aug. 9, 2017, 2:44 p.m.
As long as the reader understands lambdas I think this is a great solution.

PavloV on Sept. 2, 2017, 11:54 p.m.
Ok, first, I like it, it’s neat, for python devs it’s very VERY important. Second, I’m surprised it passed validation, also I would somewhat debate its efficiency. Validation – reasons clearly addressed a few times already by previous participants. Task: “The password contains only ASCII latin letters or digits.” So, isalpha() clearly cuts a corner. Now suggested fix isalnum() does not really do anything. I would humbly suggest introducing a “set” for example. Something like: <pre class='brush: python'>a = set('ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789') if set(s).issubset(a): … </pre> Also if someone is into speed, it may not be critical for a problem like this (House Password afterall), loop would be probably a better idea, since one may interrupt it when password criteria is met. Also lambda, I believe, is a bit slower than regular function def. I apologize if I went too far with my suggestions, for those would probably alter neat (clear) perception of a discussed solution. <hr /> Respect to author and participants of any level. :)

dudas on Nov. 11, 2017, 11:36 p.m.
Hi, unless there are some more lines to your suggestion, I don't understand how it works. for examples - s='1234567890' set(s).issubset(a) returns True (which off-course is True)

PavloV on Nov. 22, 2017, 4:31 p.m.
Oh yes, there are more lines. :( Here's a link: <a href="https://py.checkio.org/mission/house-password/publications/PavloV/python-3/should-be-quick-though-10-lines-no-imports-only-latin-letters-per-instructions/">https://py.checkio.org/mission/house-password/publications/PavloV/python-3/should-be-quick-though-10-lines-no-imports-only-latin-letters-per-instructions/</a> Certainly not the best solution but it should be faster than lambda (if that's relevant to anyone), plus addresses that "ASCII latin letters" issue.

TriphiusFire on Dec. 9, 2017, 7:16 a.m.
beautiful :) and i like that it doesn't require re import like everyone else's

My_Dlum on Feb. 18, 2018, 11:39 a.m.
this is hack, not solution!

antcontreras on Feb. 21, 2018, 9:56 a.m.
Goes to show that knowing your functions is he way to get ahead. My old linear-style thinking resulted in 34 lines...

HiJay on April 23, 2018, 9:42 a.m.
I think it's the greatest way to solve this question using lambda

Serg900vd on Feb. 5, 2022, 7:30 a.m.
This test fails: <pre class='brush: python'>assert checkio('!!!!!!!!!!!!!!!') == False </pre>

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