Reading — step 1 of 5
Read
~1 min readProduction
Putting It All Together
You've built every layer:
| Layer | Lesson |
|---|---|
| Basics | 1 |
| Delimiters | 2 |
| Quoting | 3 |
| Multi-line | 4 |
| Edge cases | 5 |
| Writing | 6 |
| Streaming | 7 |
Beyond:
- Type inference: pandas guesses column types from sample rows. Often wrong; use explicit dtypes.
- Schema validation: pandera, great_expectations check constraints.
- Streaming with mmap: for max throughput, mmap + pointer arithmetic. xsv does this.
- Compressed CSV: gzip-streamed CSVs are common (
zcat | head | csvtool). - Apache Arrow: in-memory columnar format. Faster for analytics; CSV → Arrow → Parquet pipelines are standard.
Use cases:
- Data import/export between systems
- Spreadsheets (Excel, Google Sheets, Numbers)
- Database dumps (
COPY TOin PostgreSQL) - Machine learning datasets
- Configuration files (rare but happens)
CSV is INFURIATINGLY common. Knowing the edge cases saves you from data corruption nightmares.
Discussion
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