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Introduction to Python NumPy Splitting Array

Python NumPy Splitting Array​

In NumPy, you can split an array into multiple smaller arrays along a specified axis using different functions.

Here are some common functions for splitting arrays:

Using np.split()​

The np.split() function splits an array into multiple sub-arrays along a specified axis. It takes three arguments: the array to be split, the number of equally-sized sub-arrays to create, and the axis along which to split the array.

import numpy as np

arr = np.array([1, 2, 3, 4, 5, 6])

# Split the array into three sub-arrays along the first axis (axis=0)
result = np.split(arr, 3)
print(result)

Output:

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

Using np.array_split()​

The np.array_split() function is similar to np.split(), but it allows for unequal division of the array.

You can specify the number of sub-arrays to create, and it will try to evenly distribute the elements among the sub-arrays.

import numpy as np

arr = np.array([1, 2, 3, 4, 5, 6, 7])

# Split the array into four sub-arrays using np.array_split()
result = np.array_split(arr, 4)
print(result)

Output:

[array([1, 2]), array([3, 4]), array([5, 6]), array([7])]

Using np.hsplit() and np.vsplit()​

The np.hsplit() function splits an array horizontally along the second axis (columns), while np.vsplit() splits an array vertically along the first axis (rows).

import numpy as np

arr = np.array([[1, 2, 3], [4, 5, 6], [7, 8, 9]])

# Split the array horizontally (columns) using np.hsplit()
hsplit_result = np.hsplit(arr, 3)
print(hsplit_result)

# Split the array vertically (rows) using np.vsplit()
vsplit_result = np.vsplit(arr, 3)
print(vsplit_result)

Output:

[array([[1],
       [4],
       [7]]), array([[2],
       [5],
       [8]]), array([[3],
       [6],
       [9]])]
[array([[1, 2, 3]]), array([[4, 5, 6]]), array([[7, 8, 9]])]

Splitting 2-D Arrays​

When splitting a 2D NumPy array, you can use the functions np.split(), np.hsplit(), and np.vsplit() to split the array into smaller sub-arrays along different axes.

Here are some examples:

Using np.split()​

The np.split() function can be used to split a 2D array into multiple sub-arrays along a specified axis.

import numpy as np

arr = np.array([[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12]])

# Split the array into two sub-arrays along the second axis (columns)
result = np.split(arr, 2, axis=1)
print(result)

Output:

[array([[1, 2],
       [5, 6],
       [9, 10]]), array([[3, 4],
       [7, 8],
       [11, 12]])]

Using np.hsplit()​

The np.hsplit() function splits a 2D array horizontally along the second axis (columns) into multiple sub-arrays.

import numpy as np

arr = np.array([[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12]])

# Split the array horizontally (columns) into two sub-arrays
hsplit_result = np.hsplit(arr, 2)
print(hsplit_result)

Output:

[array([[1, 2],
       [5, 6],
       [9, 10]]), array([[3, 4],
       [7, 8],
       [11, 12]])]

Using np.vsplit()​

The np.vsplit() function splits a 2D array vertically along the first axis (rows) into multiple sub-arrays.

import numpy as np

arr = np.array([[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12]])

# Split the array vertically (rows) into two sub-arrays
vsplit_result = np.vsplit(arr, 2)
print(vsplit_result)

Output:

[array([[1, 2, 3, 4],
       [5, 6, 7, 8]]), array([[ 9, 10, 11, 12]])]