Python how to combine two matrices in numpy

Use numpy.concatenate:

>>> import numpy as np
>>> np.concatenate((A, B))
matrix([[ 1.,  2.],
        [ 3.,  4.],
        [ 5.,  6.]])

You can use numpy.vstack:

>>> np.vstack((A,B))
matrix([[ 1.,  2.],
        [ 3.,  4.],
        [ 5.,  6.]])