Numpy: Stack arrays

# Import library
import numpy as np

# Create arrays
x = np.array([[1,2],[3,4]])
y = np.array([[10,20],[30,40]])

print("x:\n", x)
print('shape:',x.shape, '\n')
print("y:\n", y)
print('shape:',y.shape, '\n')

x:
 [[1 2]
 [3 4]]
shape: (2, 2) 

y:
 [[10 20]
 [30 40]]
shape: (2, 2)

# Stack
sh = np.stack((x,y), axis = 0)
sv = np.stack((x,y), axis = -1)

# Output
print("Stack (axis=0):\n", sh)
print('shape:',sh.shape, '\n')
print("Stack (axis=-1):\n", sv)
print('shape:',sv.shape, '\n')

Stack (axis=0):
 [[[ 1  2]
  [ 3  4]]

 [[10 20]
  [30 40]]]
shape: (2, 2, 2) 

Stack (axis=-1):
 [[[ 1 10]
  [ 2 20]]

 [[ 3 30]
  [ 4 40]]]
shape: (2, 2, 2)

# Stack
hs = np.hstack((x,y))

# Output
print("hstack:\n", hs)
print('shape:',hs.shape, '\n')

hstack:
 [[ 1  2 10 20]
 [ 3  4 30 40]]
shape: (2, 4) 

# Stack
vs = np.vstack((x,y))

# Output
print("vstack:\n", vs)
print('shape:',vs.shape, '\n')

vstack:
 [[ 1  2]
 [ 3  4]
 [10 20]
 [30 40]]
shape: (4, 2)