Question

I want to get the c array as result, but I don’t know how:

import numpy as np
a = xrange(10)
b = np.array([3,2,1,9])

c is made of elements of a that are not in b:

c = np.array([0,4,5,6,7,8])

Answer 1

Perhaps a more straightforward solution is the following:

import numpy as np
a = xrange(10)
b = np.array([3,2,1,9])

c = np.setdiff1d(a,b)

Which results in:

In [7]: c
Out[7]: array([0, 4, 5, 6, 7, 8])

You can find all of the set-like operations for numpy arrays in the documentation:
http://docs.scipy.org/doc/numpy/reference/routines.set.html