# LightGBM Transformation Library

The LightGBM transformation library aims at providing a flexible and automatic way to do feature transformation when using [`LightGBM`](https://github.com/microsoft/LightGBM). Compared to separate transformation. this way has several pros:

- More efficient. Data preprocessing can go with parsing each line, and take advantage of multi-processing designed by lightgbm naturally. No need to store whole transformed data in file/memory.
- More convenient for development and iteration. Built-in transformation could keep offline and online consistent well by saved/loaded along with model.

In the repo, user could learn about:

- How to customize favorite parser by playing with LightGBM Parser interface.
- How to use [`FreeForm2Parser`](./examples/freeform2_parser.cpp), a powerful and efficient tool built in the repo, in model training. Instead of handling data yourself, user just need to prepare a feature spec which contains feature name, transform type and expression, and make slight changes in experiment iterations.

## Get Started and Documentation

- [Installation guide](./docs/Installation-Guide.rst)
- [Customized parser tutorial](./docs/Customized-Parser-Tutorial.rst)
- [Transform tutorial](./docs/Transform-Tutorial.rst)
- [FreeForm2 language spec](./docs/FreeForm2-Language.rst)

## Contributing

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