This document provides an overview of week 4 topics for a Code Club on wrangling data with Python. The key points covered are: - Merging data from different data frames and working with "tidy data" formats. - Taking first steps in reshaping datasets, including long to wide data transforms and pivots. - Various strategies for cleaning datasets, such as handling empty/duplicate rows and columns, cleaning text strings, and mapping values. - The melt and pivot functions for reshaping data between wide and long formats.