Pythonic way to check if two lists are equal in size

Asked Oct 25 '17 at 18:50

Active Oct 25 '17 at 18:50

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Whats the most pythonic or efficent way to check if two lists are equal in size?

The only thing I can think of is

len(list_a) == len(list_b)

but that seems like it would take a lot more processing power than necessary, especially if the check needs to be done frequently and on large lists.

Is there a better way?

asked Oct 25 '17 at 18:50

Reimus Klinsman

2

Why would this require a lot of processing power? – Willem Van Onsem Oct 25 '17 at 18:50
Oh, I'm under the impression that `len` counts the list each time it's called, so each time this condition is called, it'd count two lists that might be millions of elements in length. I very well could be wrong and the list itself could store the count and `len` just returns that count – Reimus Klinsman Oct 25 '17 at 18:53
1

Profile the code first – NuclearPeon Oct 25 '17 at 18:53
6

@KeiNagase: no, a list stores the number of elements explicitly, so it is an *O(1)* operation. – Willem Van Onsem Oct 25 '17 at 18:53
1

No, this works in constant time, and is as fast as you could get. – juanpa.arrivillaga Oct 25 '17 at 18:54

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