I have two nested lists:

a = [[1,2,3],[2,4,2]]
b = [[5,5,5],[1,1,1]]

I want to multiply and SUMPRODUCT each group of elements to get

c = [[30],[8]]

Which result from = [[1*5+2*5+3*5],[2*1,4*1,2*1]]

I´ve tried doing:

c = sum(x * y for x, y in zip(a, b))

But I get "can't multiply sequence by non-int of type 'list'"

Is there a simple list comprehension way to do this avoiding for loops?

You can implement the dotproduct itertools recipes:

import operatordef dotproduct(vec1, vec2):return sum(map(operator.mul, vec1, vec2))

Code

a = [[1,2,3], [2,4,2]] 
b = [[5,5,5], [1,1,1]][[dotproduct(x, y)] for x, y in zip(a, b)]
# [[30], [8]]