Replacing Values in Pandas DataFrames Based on Certain Conditions Using map, Series, and Set Index

Adding a Description to Python Dataframe Before Column Headers When Exporting as Text.

Filtering Similar Rows in a Dictionary Using Python's Pandas and Multiprocessing Libraries

Here's a more detailed explanation of how to achieve this using Python:

Handling Missing Dates in a DataFrame: A Comprehensive Guide to Dealing with Missing Values in Date Columns

Comparing Dictionaries and DataFrames in Python: A Comprehensive Guide

Extracting Values from a 'Names' Column within a Pandas Series Object: A Step-by-Step Guide

To calculate the sum of sales for each salesman in a month before their training date, we need to group by "salesman" and "transaction_month", then apply the aggregation function `sum` to the 'sales' column.

Maintaining Value of Last Row in Column Based on Conditions from Adjacent Columns Using Pandas in Python

Converting DataFrameGroupBy Object to Dictionary without Index Column: Customized Solutions and Alternatives