Python Pandas - Create a PeriodIndex and set frequency

To create a PeriodIndex, use the pandas.PeriodIndex() method. To set the frequency, use the freq parameter for representing regular periods in time.

What is PeriodIndex?

A PeriodIndex is an immutable ndarray that holds ordinal values indicating regular periods in time. It's useful for time series data where you want to represent periods rather than timestamps.

Creating a Basic PeriodIndex

Here's how to create a PeriodIndex with daily frequency ?

import pandas as pd

# Create a PeriodIndex with daily frequency
period_index = pd.PeriodIndex(['2021-09-25', '2020-10-30', '2020-11-20'], freq="D")

print("PeriodIndex...")
print(period_index)

PeriodIndex...
PeriodIndex(['2021-09-25', '2020-10-30', '2020-11-20'], dtype='period[D]')

Different Frequency Options

You can use various frequency parameters to create different period types ?

import pandas as pd

# Monthly frequency
monthly = pd.PeriodIndex(['2021-09', '2021-10', '2021-11'], freq="M")
print("Monthly PeriodIndex:")
print(monthly)

# Yearly frequency
yearly = pd.PeriodIndex(['2021', '2022', '2023'], freq="Y")
print("\nYearly PeriodIndex:")
print(yearly)

Monthly PeriodIndex:
PeriodIndex(['2021-09', '2021-10', '2021-11'], dtype='period[M]')

Yearly PeriodIndex:
PeriodIndex(['2021', '2022', '2023'], dtype='period[Y-DEC]')

Accessing Period Properties

You can extract specific components from the PeriodIndex ?

import pandas as pd

period_index = pd.PeriodIndex(['2021-09-25', '2020-10-30', '2020-11-20'], freq="D")

print("Original PeriodIndex:")
print(period_index)

print("\nDay component:")
print(period_index.day)

print("\nMonth component:")
print(period_index.month)

print("\nYear component:")
print(period_index.year)

Original PeriodIndex:
PeriodIndex(['2021-09-25', '2020-10-30', '2020-11-20'], dtype='period[D]')

Day component:
Index([25, 30, 20], dtype='int64')

Month component:
Index([9, 10, 11], dtype='int64')

Year component:
Index([2021, 2020, 2020], dtype='int64')

Common Frequency Codes

Conclusion

Use pd.PeriodIndex() with the freq parameter to create period-based time indices. PeriodIndex is ideal for representing regular time periods in data analysis and time series operations.