Find lowest index of array's slices having lowest average of elements (in Python)

min_avg_slice.py

def solution(A):
    min_avg_value = (A[0] + A[1])/2.0   # The mininal average
    min_avg_pos = 0     # The begin position of the first 
                        # slice with mininal average
 
    for index in xrange(0, len(A)-2):
        # Try the next 2-element slice
        if (A[index] + A[index+1]) / 2.0 < min_avg_value:
            min_avg_value = (A[index] + A[index+1]) / 2.0
            min_avg_pos = index
        # Try the next 3-element slice
        if (A[index] + A[index+1] + A[index+2]) / 3.0 < min_avg_value:
            min_avg_value = (A[index] + A[index+1] + A[index+2]) / 3.0
            min_avg_pos = index
 
    # Try the last 2-element slice
    if (A[-1]+A[-2])/2.0 < min_avg_value:
        min_avg_value = (A[-1]+A[-2])/2.0
        min_avg_pos = len(A)-2
 
    return min_avg_pos

source: http://codesays.com/2014/solution-to-min-avg-two-slice-by-codility/