numpy.unique() function with example program in python

Spread the love

numpy.unique(): This function find the unique elements of an array.

Syntax: numpy.unique(ar, return_index=False, return_inverse=False, return_counts=False, axis=None)

Returns the sorted unique elements of an array. There are three optional outputs in addition to the unique elements:

the indices of the input array that give the unique values
the indices of the unique array that reconstruct the input array
the number of times each unique value comes up in the input array

Parameters:
ar : array_like
Input array. Unless axis is specified, this will be flattened if it is not already 1-D.

return_index : bool, optional
If True, also return the indices of ar (along the specified axis, if provided, or in the flattened array) that result in the unique array.

return_inverse : bool, optional
If True, also return the indices of the unique array (for the specified axis, if provided) that can be used to reconstruct ar.

return_counts : bool, optional
If True, also return the number of times each unique item appears in ar.

New in version 1.9.0.

axis : int or None, optional
The axis to operate on. If None, ar will be flattened. If an integer, the subarrays indexed by the given axis will be flattened and treated as the elements of a 1-D array with the dimension of the given axis, see the notes for more details. Object arrays or structured arrays that contain objects are not supported if the axis kwarg is used. The default is None.

New in version 1.13.0.

Returns:
unique : ndarray
The sorted unique values.

unique_indices : ndarray, optional
The indices of the first occurrences of the unique values in the original array. Only provided if return_index is True.

unique_inverse : ndarray, optional
The indices to reconstruct the original array from the unique array. Only provided if return_inverse is True.

unique_counts : ndarray, optional
The number of times each of the unique values comes up in the original array. Only provided if return_counts is True.

New in version 1.9.0.

Example Program:

import numpy as np a= np.array([1,2,2,3,4,5,5,9]) b=np.unique(a) print(b)

Output:

[1 2 3 4 5 9]

 

admin

admin

Leave a Reply

Your email address will not be published. Required fields are marked *