Find the row indexes of several values in a numpy array

Question

I have an array X:

X = np.array([[4,  2],
              [9,  3],
              [8,  5],
              [3,  3],
              [5,  6]])

And

Answer 1

X = np.array([[4,  2],
              [9,  3],
              [8,  5],
              [3,  3],
              [5,  6]])

S = np.array([[4, 2],
              [3, 3],
              [5, 6]])

result = [[i for i,row in enumerate(X) if (s==row).all()] for s in S]

or

result = [i for s in S for i,row in enumerate(X) if (s==row).all()]

if you want a flat list (assuming there is exactly one match per searched value).