>>> import numpy as np
>>> a = np.array([3,8,12,18,7,11,30])
>>> a[1::2]
array([ 8, 18, 11])
>>> a[::-1]
array([30, 11, 7, 18, 12, 8, 3])
>>> m = np.array([ [11, 12, 13, 14], [21, 22, 23, 24], [31, 32, 33, 34]])
>>> m[::,::-1]
array([[14, 13, 12, 11],
[24, 23, 22, 21],
[34, 33, 32, 31]])
>>> m[::-1]
array([[31, 32, 33, 34],
[21, 22, 23, 24],
[11, 12, 13, 14]])
>>> m[::-1,::-1]
array([[34, 33, 32, 31],
[24, 23, 22, 21],
[14, 13, 12, 11]])
>>> m[1:-1,1:-1]
array([[22, 23]])