ETL

Pandas melt and stack Producing Duplicate Rows: Reshaping Pitfalls Fixed

Reshaping data with Pandas melt() and stack() is a common task in analytics pipelines, but many developers are surprised when the resulting dataset contains duplicate rows, inflated record counts, or incorrect aggregations. Learn why these issues occur and how to avoid them.

Jun 28, 2026 4m read 👁 1

Fixing Python xlsxwriter That Generates Duplicate Header Rows on Sheet Merge

Merging multiple sheets into one with xlsxwriter and ending up with headers sprinkled throughout your data? Here's exactly why that happens and how to write the merge loop that gets it right every time.

Jun 27, 2026 9m read 👁 14