Python Pandas - Return unique values in the index

To return unique values in a Pandas index, use the index.unique() method. This method returns unique values in their order of first appearance without sorting them.

Syntax

index.unique()

Creating a Pandas Index

First, let's create a Pandas index with duplicate values ?

import pandas as pd

# Creating Pandas index with duplicates
index = pd.Index([10, 50, 70, 10, 90, 50, 10, 30])
print("Original Index:")
print(index)

Original Index:
Int64Index([10, 50, 70, 10, 90, 50, 10, 30], dtype='int64')

Getting Unique Values

Use the unique() method to extract unique values. The values are returned in order of appearance ?

import pandas as pd

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

# Get unique values from the index
unique_values = index.unique()
print("Unique values:")
print(unique_values)
print(f"\nOriginal size: {index.size}")
print(f"Unique values count: {len(unique_values)}")

Unique values:
Int64Index([10, 50, 70, 90, 30], dtype='int64')

Original size: 8
Unique values count: 5

Example with String Index

The unique() method works with different data types ?

import pandas as pd

# String index with duplicates
str_index = pd.Index(['apple', 'banana', 'apple', 'cherry', 'banana', 'date'])
print("String Index:")
print(str_index)

print("\nUnique string values:")
print(str_index.unique())

String Index:
Index(['apple', 'banana', 'apple', 'cherry', 'banana', 'date'], dtype='object')

Unique string values:
Index(['apple', 'banana', 'cherry', 'date'], dtype='object')

Key Points

Conclusion

The index.unique() method efficiently extracts unique values from a Pandas index while preserving their order of appearance. Use this method when you need to remove duplicates without sorting the results.