Numpy Array: Efficiently find matching indices

Question

I have two lists, one of which is massive (millions of elements), the other several thousand. I want to do the following

bigArray=[0,1,0,2,3,2,,.....]

small         


        

Answer 1

Numpy provides the function numpy.searchsorted: http://docs.scipy.org/doc/numpy-1.10.0/reference/generated/numpy.searchsorted.html

Example:

>>> import numpy as np
>>> sorted = np.argsort(big_list)
>>> r = np.searchsorted(big_list, small_list, side='right',sorter=sorted)
>>> l  = np.searchsorted(big_list, small_list, side='left',sorter=sorted)
>>> for b, e in zip(l, r):
...     inds = sorted[b:e]