I understand the output of
np.where() with input of a one-row array. However, when a two-row array was used as an input, I don’t understand why the output of b is two arrays.
The output for a[b] makes sense.
a = np.array([[1, 2, 3],[4,5,6]]) print(a) print ('Indices of elements <4') b = np.where(a<4) print(b) print(a[b])
output for b:
(array([0, 0, 0], dtype=int64), array([0, 1, 2], dtype=int64))
output for a[b]:
[1 2 3]
We require two indices to access each element in 2D array. For eg. i and j.
Hence, if the indices of the 2D array satisfying the condition are
(i1,j1), (i2,j2) and (i3,j3) for condition
np.where() will return a tuple of tuples in format like