How to return the index of numpy ndarray based on search?

Question

I have a numpy 2D array,

import numpy as np
array1 = array([[ 1,  2,  1,  1],
   [ 2,  2,  2,  1],
   [ 1,  1,  1,  1],
   [1,  3, 1, 1],
   [1,  1, 1, 1]])

I would like to find the element '3' and know its location. So, I could try

condition = array1 == 3

and then to find the arguments, I could try

np.argwhere(condition)

How else does one locate the indices where 3 is located?

Colonel Beauvel · Accepted Answer · 2015-12-12 02:43:46Z

1

You can also use where, returning a tuple of coordinate:

In [34]: np.where(array1==3)
Out[34]: (array([3]), array([1]))

answered Dec 12, 2015 at 2:29

Colonel Beauvel

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