python/CLAUDE.md

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# CLAUDE.md — Python Module

This file provides guidance to Claude Code (claude.ai/code) when working with the Python module.

## Prerequisites

The Python module depends on the C++ shared library (`libtsfile`). **Build C++ first:**

```bash
# From repo root
./mvnw clean package -P with-cpp -DskipTests
```

## Build Commands

```bash
# Build everything via Maven (builds C++ then Python)
./mvnw clean verify -P with-python

# Or build directly (after C++ is built)
cd python
python setup.py build_ext --inplace

# Run tests
pytest tests/

# Run a single test
pytest tests/test_write_and_read.py -k "test_name"

# Format code
cd ../ && ./mvnw spotless:apply   # Uses Black 26.3.1
```

## Source Structure

```
python/tsfile/
├── __init__.py              # Public API exports
├── constants.py             # Enums: TSDataType, TSEncoding, Compressor, ColumnCategory
├── schema.py                # TimeseriesSchema, DeviceSchema, TableSchema, ColumnSchema
├── tablet.py                # Tablet class for batch columnar data
├── field.py / row_record.py # Row-based data structures
├── tag_filter.py            # Tag filtering DSL for queries
├── tsfile_table_writer.py   # High-level table writer API
├── utils.py                 # to_dataframe(), dataframe_to_tsfile()
├── exceptions.py            # Custom exception types
│
├── tsfile_py_cpp.pyx        # Cython core: Python ↔ C++ type conversion
├── tsfile_reader.pyx        # Cython reader wrapper
├── tsfile_writer.pyx        # Cython writer wrapper
├── tsfile_cpp.pxd           # C++ interface declarations (cwrapper)
│
└── dataset/                 # High-level multi-file API
    ├── dataframe.py         # TsFileDataFrame (pandas-like interface)
    ├── timeseries.py        # Timeseries, AlignedTimeseries
    ├── reader.py            # Multi-file reader coordination
    └── merge.py             # K-way merge for overlapping time ranges
```

## Architecture Notes

- **Layered design**: C++ core → Cython bridge (`*.pyx`) → Pure Python API
- `setup.py` copies pre-built C++ headers and shared libraries from `../cpp/target/build/`
- Cython binds to `cwrapper/tsfile_cwrapper.h` from the C++ module
- C error codes are mapped to Python exceptions via `check_error()` in `tsfile_py_cpp.pyx`
- Requires Python 3.9+, numpy >= 2.0, pandas >= 2.0, pyarrow >= 16.0

## Code Style

- **Formatter**: Black 26.3.1 (via Spotless Maven plugin)

## Testing

- **Framework**: pytest
- Tests in `python/tests/`, 19 test files covering write, read, filtering, DataFrame conversion, and Arrow format

## License Header

Every new file must include the Apache License 2.0 header at the top. For Python files, use `#` line comments. For `.pyx`/`.pxd` files, also use `#` comments. See any existing file for the exact wording.

## Git Commit

- Do NOT add `Co-Authored-By` trailer to commit messages.