Forust

This release adds an experimental parameter, `create_missing_branch`, that if True, will create a separate branch for missing, creating a ternary tree, the missing node will be given the same weight value as the parent node. If this parameter is False, missing will be sent down either the left or right branch, creating a binary tree. Defaults to False.

- Fixed bug where features were said to have zero variance, with low populated levels.
- Added `subsample` parameter to sample records prior to training each tree.
- Added `missing` parameter, so missing can now be assigned to any float, rather than only being `np.nan`.
- Added `metadata` store to booster object, so info can be saved on the booster and loaded again later after saving.

This release adds the `predict_contributions` method to the `GradientBooster` object, both for the Rust and Python API.

v.0.2.2
Hot fix to a bug in the contributions prediction where the base_score would be ignored. Additionally, performance improvements were made, to make contributions calculations ~5X faster.

This release is a major refactor to how splitting is handled internally, the external API and python API remain the same. With these changes it will be easier to allow for missing to be treated explicitly while training. Future releases will implement the ability to split out missing into it's own separate branch.

This release adds the following changes to the packages

- Support for monotonic constraints. Features can now be supplied with a constraint so that they are forced to either have a monotonic increasing, decreasing, or unconstrained relationship with the target variable. This can be adjusted using the `monotone_constraints` parameter.
- Experimental support for dealing with missing in different ways. This includes the ability to not allow splits on missing or non-missing alone, as well as not automatically imputing missing, and instead always sending it down a default branch instead of learning the best direction to send it. See the documentation on the `allow_missing_splits` and `allow_missing_splits` parameters.
- The default value of the `min_leaf_weight` parameter was changed from 0.0, to 1.0.
- Additional refactoring of the code to better align with modern python type hints, as well as adding pre-commit support for development, and adjusting some of the naming of modules to be clearer.

This release fixes a bug where the README and LICENSE files aren't included in the source distribution.