Time Complexity for Python built-ins?

Question

Is there any good reference resource to know the time complexity of Python's built-in functions like dict.fromkeys(), .lower()? I found links like this UCI resource which lists time-complexity for basic list & set operations but of course, not for all built-ins. I also found Python Reference - The Right Way but most of references have #TODO for time complexity.

I also tried reading the source code of python built-ins to figure out how the functions like dict.fromkeys() are implemented but felt lost.

@AChampion: Thanks for providing the link but it also doesn't provide info on time complexity for string data types, and also misses operations (like dict.fromkeys()) while listing operations on dict. — Vimanyu
– Vimanyu, Commented Jan 21, 2019 at 1:19

lifelonglearner · Accepted Answer · 2021-02-12 22:35:54Z

3

This is a great place to start:

https://wiki.python.org/moin/TimeComplexity

It says that Get Item is O(1) and Iteration is O(n) (Average Case). So then, if with .fromkeys() you iterate over just the keys of the dict, then make those the keys of a new dict, while also setting values, I'd think that you'd have between O(n) and O(2n), where n is the number of keys in the first dict.

Sorry that I can't offer more than conjecture, but hopefully that link is helpful.

answered Feb 12, 2021 at 22:35

lifelonglearner

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