Data Processing: pandas, openpyxl, lxml pandas Essentials Reading Data Selection and Filtering Data Transformation Aggregation Merge / Join Writing Data Performance Tips --- openpyxl — Excel Read/Write Read with openpyxl Write with openpyxl --- lxml — XML/HTML Parsing Parse XML Build XML Namespace Handling --- File Encoding Handling UTF-16LE (industrial formats: ABB Freelance, etc.) --- Common Patterns Template-Based Bulk File Generation Validate Excel Input Before Processing ---