Indexes of elements

Question

I have numpy array: A = np.array([1,3,5,7,9]) and B = np.array([3,3,3,5,5,5])

I want to have array C - which is index B in A. C = np.array([1,1,1,2,2,2])

How I can do it?

Answer 1

The function searchsorted provides exactly the functionality you need.

C = np.searchsorted(A, B)