Python Pandas - Return number of unique elements in the Index object

To return number of unique elements in the Index object, use the index.nunique() method in Pandas. At first, import the required libraries −

import pandas as pd

Creating Pandas index −

index = pd.Index([50, 10, 70, 110, 90, 50, 110, 90, 30])

Display the Pandas index −

print("Pandas Index...\n",index)

Get the number of unique values in the index −

print("\nCount of unique values...\n",index.nunique())

Example

Following is the code −

import pandas as pd

# Creating Pandas index
index = pd.Index([50, 10, 70, 110, 90, 50, 110, 90, 30])

# Display the Pandas index
print("Pandas Index...\n",index)

# Return the number of elements in the Index
print("\nNumber of elements in the index...\n",index.size)

# Return the dtype of the data
print("\nThe dtype object...\n",index.dtype)

# Get the unique values from the index
# Unique values are returned in order of appearance, this does NOT sort
print("\nUnique values from the Index..\n", index.unique())

# Get the number of unique values in the index
print("\nCount of unique values...\n",index.nunique())

Output

This will produce the following output −

Pandas Index...
Int64Index([50, 10, 70, 110, 90, 50, 110, 90, 30], dtype='int64')

Number of elements in the index...
9

The dtype object...
int64

Unique values from the Index..
Int64Index([50, 10, 70, 110, 90, 30], dtype='int64')

Count of unique values...
6