Two-liner creative solution for Surjection Strings by obone - python coding challenges

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Two-liner solution in Creative category for Surjection Strings by obone

def isometric_strings(str1: str, str2: str) -> bool:
    dict1, dict2 = dict(zip(str1, str2)), dict(zip(str2, str1))
    return dict1 == dict(map(reversed, dict2.items())) and dict2 == dict(map(reversed, dict1.items()))

Sept. 8, 2019

Comments:

casilda on Sept. 14, 2019, 10:31 a.m.
Could you please explain the last line? I understand that the first line creates mappings between the letters in str1 and str2, and I gather the last line compares those mappings. I just have trouble understanding what exactly is being 'reversed' (key-value pairs?), what's being 'mapped' and how they're compared.

obone on Sept. 14, 2019, 1:55 p.m.
Hello! Yes, the following construction used to reverse key-value pairs: <pre class='brush: python'>dict(map(reversed, dict2.items())) </pre> So if dict2 is {'a' : 'd', 'b' : 'e', 'c' : 'f'} then we will get {'d' : 'a', 'e' : 'b', 'f' : 'c'}. Map() applies reversed() function to every key-value pair in dict2, and this is formed into dict(). After this we compare dict1 and reversed key-value dict2. Same here with dict2 and reversed key-value dict1.

casilda on Sept. 15, 2019, 4:17 p.m.
Hi, thanks for your answer, much appreciated!! I see now, map() and reversed() work together. I thought they applied independently.

Strings Theory

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