how to extract elements from a list in python ?

Question

I feel suddenly uneasy of not being able to perform this operation easily. It could be that I'm tired, or that there's really no way (google didn't help), but...

if you have a list in python, and want to extract element at indices say 1, 2 and 5 into a new list, how do you do ?

This is how I did it, but I'm not very satisfied

>>> a
[10, 11, 12, 13, 14, 15]
>>> [x[1] for x in enumerate(a) if x[0] in [1,2,5]]
[11, 12, 15]

any better way ?

more in general, given a tuple with indices, how to use this tuple to extract the corresponding elements from a list, eventually with duplication (e.g. tuple (1,1,2,1,5) produces [11,11,12,11,15] )

Answer 1

Perhaps use this:

[a[i] for i in (1,2,5)]
# [11, 12, 15]

Answer 2

Try

numbers = range(10, 16)
indices = (1, 1, 2, 1, 5)

result = [numbers[i] for i in indices]

Answer 3

Bounds checked:

 [a[index] for index in (1,2,5,20) if 0 <= index < len(a)]
 # [11, 12, 15] 

Answer 4

I think you're looking for this:

elements = [10, 11, 12, 13, 14, 15]
indices = (1,1,2,1,5)

result_list = [elements[i] for i in indices]