Python - NumPy Array Shaping

Example : Reshaping arrays

import numpy as np
np.random.seed(100)
x = np.random.randint(10, 100, 8)
print(x, end='\n\n')
y = x.reshape(2,4)
print(y, end='\n\n')
z = x.reshape(2,2,2)
print(z, '\n\n')

Output

[18 34 77 97 89 58 20 62]
[[18 34 77 97]
 [89 58 20 62]]
[[[18 34]
  [77 97]]
 [[89 58]
  [20 62]]]

Example : Vertical Stack

import numpy as np
x = np.array([[-1, 1], [-3, 3]])
y = np.array([[-2, 2], [-4, 4]])
np.vstack((x,y))

Output

array([[-1,  1],
       [-3,  3],
       [-2,  2],
       [-4,  4]])

Example : Horizontal Stack

import numpy as np
x = np.array([[-1, 1], [-3, 3]])
y = np.array([[-2, 2], [-4, 4]])
z = np.array([[-5, 5], [-6, 6]])
np.hstack((x,y,z))

Output

array([[-1,  1, -2,  2, -5,  5],
       [-3,  3, -4,  4, -6,  6]])

Example : Splitting Vertically into two arrays

import numpy as np
x = np.arange(30).reshape(6, 5)
res = np.vsplit(x, 2) #array of arrays
print(res[0], end='\n\n')
print(res[1])

Output

[[ 0  1  2  3  4]
 [ 5  6  7  8  9]
 [10 11 12 13 14]]
[[15 16 17 18 19]
[20 21 22 23 24]
 [25 26 27 28 29]]

Example : Splitting Vertically into three arrays

import numpy as np
x = np.arange(30).reshape(6, 5)
res = np.vsplit(x, (2, 5))
print(res[0], end='\n\n')
print(res[1], end='\n\n')
print(res[2])

Output

[[0 1 2 3 4]
 [5 6 7 8 9]]
[[10 11 12 13 14]
 [15 16 17 18 19]
 [20 21 22 23 24]]
[[25 26 27 28 29]]

Example

import numpy as np
x = np.arange(10).reshape(2, 5)
res = np.hsplit(x, (2,4))
print(res[0], end='\n\n')
print(res[1], end='\n\n')
print(res[2])

Output

[[0 1]
 [5 6]]
[[2 3]
 [7 8]]
[[4]
 [9]]