python return index of all occurrences in list code example

Example 1: get all indices of a value in list python

indices = [i for i, x in enumerate(my_list) if x == "whatever"]

Example 2: get all occurrence indices in list python

a_list = [1, 2, 3, 1]

indices = []
for i in range(len(a_list)):
   if a_list[i] == 1:
      indices.append(i)

# more concise way
a_list = [1, 2, 3, 1]
indices = [index for index, element in enumerate(a_list) if element == 1]