Reading CSV Values in a Timestamp Range with pandas: 3 Efficient Approaches for Large Datasets

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.

Splitting DataFrames/Arrays with Masks: Efficient Calculations for Each Split

Understanding pandas.read_csv's Behavior with Leading Zeros and Floating Point Numbers: A Guide to Avoiding Unexpected Results When Working with CSV Files in Python