how to not count a repetitive string in list in python code example

Example 1: count occurrence in array python

arr = np.array( [1, 2, 3, 2, 1, 2])
occ = np.count_nonzero(arr==0)
print(occ)
0
occ = np.count_nonzero(arr==1)
print(occ)
2

Example 2: count values in list usiing counter

from collections import Counter