Python Pandas - Check if the index has unique values

In pandas, you can check if an index contains unique values using the is_unique property. This property returns True if all index values are unique, and False if there are duplicates.

Syntax

index.is_unique

Example with Unique Values

Let's create an index with unique values and check if it has unique values ?

import pandas as pd

# Creating an index with unique values
index = pd.Index([50, 40, 30, 20, 10])

# Display the index
print("Pandas Index...")
print(index)

# Check if the index has unique values
print("\nIs the Pandas index having unique values?")
print(index.is_unique)

Pandas Index...
Index([50, 40, 30, 20, 10], dtype='int64')

Is the Pandas index having unique values?
True

Example with Duplicate Values

Now let's see what happens when the index contains duplicate values ?

import pandas as pd

# Creating an index with duplicate values
index_with_duplicates = pd.Index([50, 40, 30, 20, 30])

# Display the index
print("Pandas Index with duplicates...")
print(index_with_duplicates)

# Check if the index has unique values
print("\nIs the Pandas index having unique values?")
print(index_with_duplicates.is_unique)

Pandas Index with duplicates...
Index([50, 40, 30, 20, 30], dtype='int64')

Is the Pandas index having unique values?
False

Practical Use Case

This property is commonly used with DataFrame indexes to ensure data integrity ?

import pandas as pd

# Create a DataFrame with duplicate index values
data = {'Name': ['Alice', 'Bob', 'Charlie', 'David'], 
        'Score': [85, 92, 78, 88]}
df = pd.DataFrame(data, index=[1, 2, 2, 3])

print("DataFrame:")
print(df)
print("\nIndex has unique values:", df.index.is_unique)

DataFrame:
      Name  Score
1    Alice     85
2      Bob     92
2  Charlie     78
3    David     88

Index has unique values: False

Conclusion

The is_unique property is a simple way to verify if a pandas index contains all unique values. This is particularly useful for data validation and ensuring proper indexing in DataFrames.