Facebook Page Twitter Page LinkedIn Page
× NumPy Tutorial NumPy Resources


The NumPy sort() function returns a sorted copy of the specified array.

Syntax

numpy.sort(a, axis=-1, kind=None, order=None)

Parameters

a Required. Specify the collection object to be sorted. It can be list, tuple, set etc.
axis Optional. Specify the axis along which to sort. If None, the array is flattened before sorting. The default is -1, which sorts along the last axis..
kind Optional. Specify sorting algorithm. It can take values from {'quicksort', 'mergesort', 'heapsort', 'stable'}. Default: 'quicksort'
order Optional. Specify string or list of strings containing fields. When a is an array with fields defined, this argument specifies the order in which the fields need to the compared.

Return Value

Returns a sorted array (ndarray) of the same type and shape as a.

Example: Using sort() without axis parameter

In the below example, sort() function is used to sort elements of a 2-D array. As the axis parameter is not provided, the sorting is done along the last axis (row-wise).

import numpy as np
Arr = np.array([[1,20,5],[21, 4, 3],[11, 5, 50]])
SortedArr = np.sort(Arr)

print("Original Array:")
print(Arr)
print("Sorted Array:")
print(SortedArr)

The output of the above code will be:

Original Array:
[[ 1 20  5]
 [21  4  3]
 [11  5 50]]

Sorted Array:
[[ 1  5 20]
 [ 3  4 21]
 [ 5 11 50]]

Example: Using sort() with axis parameter

To sort the array column-wise, axis parameter can be set to 0.

import numpy as np
Arr = np.array([[1,20,5],[21, 4, 3],[11, 5, 50]])
SortedArr = np.sort(Arr, axis=0)

print("Original Array:")
print(Arr)
print("Sorted Array:")
print(SortedArr)

The output of the above code will be:

Original Array:
[[ 1 20  5]
 [21  4  3]
 [11  5 50]]

Sorted Array:
[[ 1  4  3]
 [11  5  5]
 [21 20 50]]

Example: Using sort() with axis=None

When axis=None is used, the array is flattened before sorting as shown in the below example.

import numpy as np
Arr = np.array([[1,20,5],[21, 4, 3],[11, 5, 50]])
SortedArr = np.sort(Arr, axis=None)

print("Original Array:")
print(Arr)
print("Sorted Array:")
print(SortedArr)

The output of the above code will be:

Original Array:
[[ 1 20  5]
 [21  4  3]
 [11  5 50]]

Sorted Array:
[ 1  3  4  5  5 11 20 21 50]

Example: Using sort() with order parameter

The order can be used to specify the column priority for sorting. Consider the below example:

import numpy as np
datatype = [("name", "S10"), ("age", int)]
values =  [("John", 25),("Marry", 23), ("Adam", 30)]
Arr = np.array(values, dtype = datatype)

#sort the array based on "age" column
SortedArr = np.sort(Arr, order = "age")

print("Original Array:")
print(Arr)
print("\nSorted Array:")
print(SortedArr)

The output of the above code will be:

Original Array:
[('John', 25) ('Marry', 23) ('Adam', 30)]

Sorted Array:
[('Marry', 23) ('John', 25) ('Adam', 30)]

❮ NumPy - Functions

5