Learning immediately: https://edu.csdn.net/course/play/25878/316068?utm_source=blogtoedu
vstack and hstack
a1=np.arange(6).reshape(2,3)
print(a1)
a2=np.arange(6,12).reshape(2,3)
print(a2)
a3 = np.vstack ((a1, a2))
print(a3)
a4 = np.hstack ((a1, a2))
print (a4)
