Finding the index of an item in a list

Question

Given a list [\"foo\", \"bar\", \"baz\"] and an item in the list \"bar\", how do I get its index (1) in Python?

Answer 1

Since Python lists are zero-based, we can use the zip built-in function as follows:

>>> [i for i,j in zip(range(len(haystack)), haystack) if j == 'needle' ]

where "haystack" is the list in question and "needle" is the item to look for.

(Note: Here we are iterating using i to get the indexes, but if we need rather to focus on the items we can switch to j.)