Liangliang619-liangliangprivaterepo-excel-xlsx

Comprehensive, practical guidance for creating, editing, and analyzing Microsoft Excel .xlsx workbooks and related spreadsheet files. Explains when to treat CSV as a plain data‑exchange format versus when to keep a live workbook that preserves formulas, styles, merged cells, and worksheet structure. Key recommendations include using pandas for heavy data analysis and CSV/value extraction, and using openpyxl (or Excel libraries) when you must preserve formulas, cell styles, merged ranges, or workbook‑level metadata. The guidance highlights common pitfalls—Excel date-serial quirks (the 1900 leap-year bug, fractional day/time formats), format/locale conversions, and cross-platform differences (Excel/LibreOffice/Google Sheets)—and advises writing formulas into cells rather than hard‑coding computed results when a workbook must remain dynamic. Use cases: ETL to/from spreadsheets, reproducible models, reporting templates, and cross‑platform spreadsheet compatibility checks.