Customizing Chart Border Area Color with Matplotlib

Sorting by Frequency of Values in a Column with Pandas: A Comparative Analysis of Three Methods

Specifying Multiple Converter Dictionaries When Reading Multiple Sheets with pandas.read_excel()

Python Pandas Tutorial for Concatenating Spreadsheets

Understanding Pandas Data Types: Mastering the Object Type for Efficient Data Manipulation and Analysis

Reading and Processing Multiple Files from S3 Faster with Python, Hive, and Apache Spark

Handling Datatype Issues While Reading Excel Files to Pandas DataFrames: Practical Solutions with Custom Converters

Understanding and Resolving xlrd Errors: A Guide to Handling ValueError: invalid literal for int() with base 10: ''

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.

Positioning Matplotlib Labels for Clearer Plots