Numpy: For every element in one array, find the index in another array

Question

I have two 1D arrays, x & y, one smaller than the other. I\'m trying to find the index of every element of y in x.

I\'ve found two naive ways to do this, the fir

Answer 1

I would just do this:

indices = np.where(y[:, None] == x[None, :])[1]

Unlike your memory-hog way, this makes use of broadcast to directly generate 2D boolean array without creating 2D arrays for both x and y.