def difference_indices(a, b):
    indices = []
a_index = 0
for elem_a in a:
    found_in_b = False
b_index = 0
while not found_in_b and b_index < len(b):
    if elem_a == b[b_index]:
        found_in_b = True
b_index = b_index + 1
if not found_in_b:
    indices.append(a_index)
a_index = a_index + 1
return indices
Determine arguments where two numpy arrays intersect in Python