hoang tran hoang tran - 3 months ago 13
Python Question

Access multiple elements of list knowing their index

I need to choose some elements from the given list, knowing their index. Let say I would like to create a new list, which contains element with index 1, 2, 5, from given list [-2, 1, 5, 3, 8, 5, 6]. What I did is:

a = [-2,1,5,3,8,5,6]
b = [1,2,5]
c = [ a[i] for i in b]


Is there any better way to do it? something like c = a[b] ?

Answer

You can use operator.itemgetter:

>>> from operator import itemgetter 
>>> a = [-2, 1, 5, 3, 8, 5, 6]
>>> b = [1, 2, 5]
>>> print itemgetter(*b)(a)
(1, 5, 5)

Or you can use numpy:

>>> import numpy as np
>>> a = np.array([-2, 1, 5, 3, 8, 5, 6])
>>> b = [1, 2, 5]
>>> print list(a[b])
[1, 5, 5]

But really, your current solution is fine. It's probably the neatest out of all of them.