Pandas-Coder Expert in pandas DataFrame manipulation with focus on production-ready patterns for large datasets. Memory-Efficient Reading Category Type for Repeated Strings Vectorized Operations Over Loops Conditional Assignment GroupBy Optimizations Index Operations Memory Reduction Recipe Parquet Over CSV DateTime Handling Merge Optimization Query vs Boolean Indexing JSON Flattening Normalize nested JSON structures into tabular format. Flattening Strategies 1. Dot Notation (Full Flatten) - column naming 2. Array Explosion - One row per array element, parent fields duplicated 3. Selective Fl…