Four Python CSV Projects Teach Structured Data Handling and Validation

A developer completed a series of four Python projects centered on processing CSV files, progressing from a basic reader to a sales report. The first project used DictReader to read rows as dictionaries and fell back to a zero price when conversion failed. Later projects added filtering, calculation of product statistics through separate functions, and detailed error reporting with rejected rows saved to a separate file via DictWriter. A key challenge was retaining data after a file closes, which was solved by storing valid and rejected records in Python lists. The final sales report combined these concepts into a more complex workflow.