Efficiently replace elements in array based on dictionary - NumPy / Python

Question

First, of all, my apologies if this has been answered elsewhere. All I could find were questions about replacing elements of a given value, not elements of multiple values.<

Answer 1

I think the Divakar #3 method assumes that the mapping dict covers all values (or at least the maximum value) in the target array. Otherwise, to avoid index out of range errors, you have to replace the line

mapping_ar = np.zeros(k.max()+1,dtype=v.dtype) with

mapping_ar = np.zeros(array.max()+1,dtype=v.dtype)

That adds considerable overhead.