creating sum of odd indexes python

Question

I'm trying to create a function equal to the sum of every other digit in a list. For example, if the list is [0,1,2,3,4,5], the function should equal 5+3+1. How could I do this? My knowledge of Python does not extend much farther than while and for loops. Thanks.

Answer 1

Here is a simple one-liner:

In [37]: L
Out[37]: [0, 1, 2, 3, 4, 5]

In [38]: sum(L[1::2])
Out[38]: 9

In the above code, L[1::2] says "get ever second element in L, starting at index 1"

Here is a way to do all the heavy lifting yourself:

L = [0, 1, 2, 3, 4, 5]
total = 0
for i in range(len(L)):
    if i%2:  # if this is an odd index
        total += L[i]

Here's another way, using enumerate:

L = [0, 1, 2, 3, 4, 5]
total = 0
for i,num in enumerate(L):
    if i%2:
        total += num