Let's say the array is **b=np.array([1,0,0,0,1,1,1,0,0,1,1,1,0])**. How can I find the indices of all 1 in b?

+1 vote

Best answer

You can use **numpy.where()**. It returns a tuple, so you need to take the first element of the tuple for the result.

Check the following example:

>>> b=np.array([1,0,0,0,1,1,1,0,0,1,1,1,0,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,1,1,0,0,1,1])

>>> np.where(b==1)[0]

array([ 0, 4, 5, 6, 9, 10, 11, 13, 14, 15, 16, 17, 18, 29, 30, 33, 34],

dtype=int64)