You can use the following methods to count unique values in a NumPy array:

**Method 1: Display Unique Values**

np.unique(my_array)

**Method 2: Count Number of Unique Values**

len(np.unique(my_array))

**Method 3: Count Occurrences of Each Unique Value**

np.unique(my_array, return_counts=True)

The following examples show how to use each method in practice with the following NumPy array:

import numpy as np #create NumPy array my_array = np.array([1, 3, 3, 4, 4, 7, 8, 8])

**Example 1: Display Unique Values**

The following code shows how to display the unique values in the NumPy array:

#display unique values np.unique(my_array) array([1, 3, 4, 7, 8])

From the output we can see each of the unique values in the NumPy array: 1, 3, 4, 7, 8.

**Example 2: Count Number of Unique Values**

The following code shows how to count the total number of unique values in the NumPy array:

#display total number of unique values len(np.unique(my_array)) 5

From the output we can see there are **5** unique values in the NumPy array.

**Example 3: Count Occurrences of Each Unique Value**

The following code shows how to count the number of occurrences of each unique value in the NumPy array:

#count occurrences of each unique value np.unique(my_array, return_counts=True) (array([1, 3, 4, 7, 8]), array([1, 2, 2, 1, 2]))

The first array in the output shows the unique values and the second array shows the count of each unique value.

We can use the following code to print this output in a format that is easier to read:

#get unique values and counts of each value unique, counts = np.unique(my_array, return_counts=True) #display unique values and counts side by side print(np.asarray((unique, counts)).T) [[1 1] [3 2] [4 2] [7 1] [8 2]]

From the output we can see:

- The value 1 occurs
**1**time. - The value 3 occurs
**2**times. - The value 4 occurs
**2**times. - The value 7 occurs
**1**time. - The value 8 occurs
**2**times.

**Additional Resources**

The following tutorials explain how to perform other common operations in Python:

How to Calculate the Mode of NumPy Array

How to Map a Function Over a NumPy Array

How to Sort a NumPy Array by Column