Python Basics

numpy.split() in Python | np.split() in Python

NumPy split() function is used to split an array into more than one sub-arrays.

Syntax of numpy.split()

numpy.split(arr, indices, axis=0)

arr parameter refers to Numpy array that we want to split.

indices parameter can be integer value or 1-D sorted Numpy integer array. If the value of indices is an integer(N) then array will be divided into N equal sub-arrays. If the value of indices is 1-D sorted integer array then array is divided as per sorted integer. For eg:

indices is [3, 4] & axis is 0 then splitting will be like this-

arr[:3], arr[3:4], and arr[4:]

axis parameter is used to specify the axis along which you want to split array.

Note: np.split() function returns a list of sub-arrays.

Python program to split 1-D Numpy array

import numpy as np
 
x = np.array([1, 2, 3, 4])
subx = np.split(x, 2)
print('Splitting of array x:\n', subx)
print('Accessing 0th element of sub-array:', subx[0])
y = np.array([21, 8, 42, 95, 76, 35])
suby = np.split(y, [2, 3])
print('Splitting of array y:\n', suby)
print('Accessing 2nd element of sub-array:', suby[2])

Output of the above program

Splitting of array x:
 [array([1, 2]), array([3, 4])]
Accessing 0th element of sub-array: [1 2]
Splitting of array y:
 [array([21,  8]), array([42]), array([95, 76, 35])]
Accessing 2nd element of sub-array: [95 76 35]

The code np.split(x, 2) has splitted Numpy array x into two equal sub-arrays- [1, 2] and [3, 4]

The code np.split(y, [2, 3]) has splitted array y into three sub-arrays- y[:2], y[2:3] and y[3:]

Python program to split 2-D Numpy array

import numpy as np

x = np.array([[1, 2, 3, 4, 5], [6, 7, 8, 9, 10]])
print('Splitting array into 2 equal parts along axis=0:\n', np.split(x, 2, axis=0))
print('Splitting array into 5 equal parts along axis=1:\n', np.split(x, 5, axis=1))

Output of the above program

Splitting array into 2 equal parts along axis=0:
 [array([[1, 2, 3, 4, 5]]), array([[ 6,  7,  8,  9, 10]])]
Splitting array into 5 equal parts along axis=1:
 [array([[1],
       [6]]), array([[2],
       [7]]), array([[3],
       [8]]), array([[4],
       [9]]), array([[ 5],
       [10]])]

The code np.split(x, 2, axis=0) has splitted Numpy array x into two equal sub-arrays- [[1, 2, 3, 4, 5]] and [[ 6, 7, 8, 9, 10]]

The code np.split(x, 5, axis=1) has splitted array x into five equal sub-arrays- [[1], [6]], [[2], [7]], [[3], [8]], [[4], [9]] and [[5], [10]]

Python Basics

numpy.split() in Python | np.split() in Python

Syntax of numpy.split()

Python program to split 1-D Numpy array

Python program to split 2-D Numpy array

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