Understanding Backslashes in Python Strings: A Comprehensive Guide

Filtering Pandas Series with Masking: A Comprehensive Guide

Skipping Non-Dictionary Values in JSON Data with Python Pandas

Selecting Column Names in Python Pandas by DataFrame Values

Comparing Columns from Two DataFrames in Python: A Comprehensive Guide

Understanding Floating Point Objects and Iterability: Workarounds for Limitations in Python Code

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.

Accessing Data with `iloc` or Other Method for More Than One Item Using Loop in It

Summing Values in a Column Using Conditional Statements of Other Columns in a Pandas DataFrame

Optimizing Memory Usage in Python's Multiprocessing Module: A Guide to Determining an Optimal Value for maxTasksPerChild