Skip to content
Related Articles
How to count the frequency of unique values in NumPy array?
• Last Updated : 02 Sep, 2020

Let’s see How to count the frequency of unique values in NumPy array. Python’s numpy library provides a numpy.unique() function to find the unique elements and it’s corresponding frequency in a numpy array.

Syntax: numpy.unique(arr, return_counts=False)

Return: Sorted unique elements of an array with their corresponding frequency counts NumPy array.

Now, Let’s see examples:

Example 1:

## Python3

 `# import library``import` `numpy as np`` ` `ini_array ``=` `np.array([``10``, ``20``, ``5``,``                      ``10``, ``8``, ``20``,``                      ``8``, ``9``])`` ` `# Get a tuple of unique values ``# and their frequency in``# numpy array``unique, frequency ``=` `np.unique(ini_array, ``                              ``return_counts ``=` `True``)``# print unique values array``print``(``"Unique Values:"``, ``      ``unique)`` ` `# print frequency array``print``(``"Frequency Values:"``,``      ``frequency)`

Output:

```Unique Values: [ 5  8  9 10 20]
Frequency Values: [1 2 1 2 2]
```

Example 2:

## Python3

 `# import library``import` `numpy as np`` ` `# create a 1d-array``ini_array ``=` `np.array([``10``, ``20``, ``5``,``                    ``10``, ``8``, ``20``,``                    ``8``, ``9``])`` ` `# Get a tuple of unique values ``# amnd their frequency ``# in numpy array``unique, frequency ``=` `np.unique(ini_array,``                              ``return_counts ``=` `True``) `` ` `# convert both into one numpy array``count ``=` `np.asarray((unique, frequency ))`` ` `print``(``"The values and their frequency are:\n"``,``     ``count)`

Output:

```The values and their frequency are:
[[ 5  8  9 10 20]
[ 1  2  1  2  2]]```

Example 3:

## Python3

 `# import library``import` `numpy as np`` ` `# create a 1d-array``ini_array ``=` `np.array([``10``, ``20``, ``5``,``                      ``10``, ``8``, ``20``,``                      ``8``, ``9``])`` ` `# Get a tuple of unique values ``# and their frequency in``# numpy array``unique, frequency ``=` `np.unique(ini_array, ``                              ``return_counts ``=` `True``) `` ` `# convert both into one numpy array ``# and then transpose it``count ``=` `np.asarray((unique,frequency )).T`` ` `print``(``"The values and their frequency are in transpose form:\n"``,``     ``count)`

Output:

```The values and their frequency are in transpose form:
[[ 5  1]
[ 8  2]
[ 9  1]
[10  2]
[20  2]]```

Attention geek! Strengthen your foundations with the Python Programming Foundation Course and learn the basics.

To begin with, your interview preparations Enhance your Data Structures concepts with the Python DS Course. And to begin with your Machine Learning Journey, join the Machine Learning – Basic Level Course

My Personal Notes arrow_drop_up