>>> a = np.array([
[11,12,13,14,15],
[21,22,23,24,25],
[31,32,33,34,35],
[41,42,43,44,45],
[51,52,53,54,55]])
>>> a[:3,2:]
array([[13, 14, 15],
[23, 24, 25],
[33, 34, 35]])
>>> a[3:,:]
array([[41, 42, 43, 44, 45],
[51, 52, 53, 54, 55]])
>>> a[:,4:]
array([[15],
[25],
[35],
[45],
[55]])