In [15]:
import numpy as np

ar = np.array([[1,2,3],
                  [2,3,4]])
print ar[1,]

#vstack hstack
#concatenate
print np.mean(ar, axis=(0,1))
print np.median(ar)
print np.diff(ar)
#ar.flat   ar.flatten()
#np.array_split


[2 3 4]
2.5
2.5
[[1 1]
 [1 1]]