how to find index of value in numpy array code example

Example 1: indexing a numpy array in python

array = [[0  1  2  3  4  5] 
  [6 7 8 9 10 11]
  [12 13 14 15 16 17]
  [18 19 20 21 22 23]
  [24 25 26 27 28 29]
  [30 31 32 33 34 35]]
array[0, 3:5]  =  [3 4]

array[4:, 4:] = [[28 29],
             [34 35]]

array[:, 2] =  [2 8 14 20 26 32]

array[2:;2, ::2] = [[12 14 16],
                [24 26 28]]

Example 2: numpy find index of matching values

import numpy as np
# init arrays
a = np.array([1,2,3,2,3,4,3,4,5,6])
b = np.array([7,2,10,2,7,4,9,4,9,8])

#using enumerate, list comprehension and set
print([key for key, val in enumerate(a) if val in set(b)])
# output
# [1, 3, 5, 7]