Picking out items from a python list which have specific indexes

python list list-comprehension
Ben picture Ben · Apr 7, 2009 · Viewed 56.9k times · Source

I'm sure there's a nice way to do this in Python, but I'm pretty new to the language, so forgive me if this is an easy one!

I have a list, and I'd like to pick out certain values from that list. The values I want to pick out are the ones whose indexes in the list are specified in another list.

For example:

indexes = [2, 4, 5]
main_list = [0, 1, 9, 3, 2, 6, 1, 9, 8]

the output would be:

[9, 2, 6]

(i.e., the elements with indexes 2, 4 and 5 from main_list).

I have a feeling this should be doable using something like list comprehensions, but I can't figure it out (in particular, I can't figure out how to access the index of an item when using a list comprehension).

Answer

Matthew Schinckel picture Matthew Schinckel · Apr 7, 2009 
[main_list[x] for x in indexes]

This will return a list of the objects, using a list comprehension.

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