chimeraboost 0.6.0

CatBoost-inspired gradient boosting in pure Python with a numba backend

chimeraboost

What if CatBoost, but way faster, slightly worse, and all in Python?

• What?

  • GBDT library that only depends on common Python libraries
  • Supports regression, binary and multiclass classification, quantile regression
  • Categorical features, sample weights, and automatic early stopping
  • Within ~3% F1 / ~5% RMSE of CatBoost on a 34-dataset OpenML benchmark, at ~18× the speed

• Why?

  • I want to be able to modify my GBDT library at will
  • I know Python and I don't know C

• Install

pip install chimeraboost

• How?

from chimeraboost import ChimeraBoostClassifier, ChimeraBoostRegressor

# classification
clf = ChimeraBoostClassifier(early_stopping=True)
clf.fit(X, y, cat_features=[0, 1], sample_weight=w)
proba = clf.predict_proba(X_test)

# regression (RMSE, MAE, or Quantile)
reg = ChimeraBoostRegressor(loss="Quantile", alpha=0.9, early_stopping=True)
reg.fit(X, y)

• Some parameters

Param	Default	What it does
iterations	500	Max boosting rounds (capped earlier by early stopping).
learning_rate	auto	Per-round shrinkage; auto-picked when None.
depth	6	Oblivious-tree depth (same split applied across each level).
l2_leaf_reg	3.0	L2 regularization on leaf values.
max_bins	128	Quantile bins per numeric feature.
cat_n_permutations	4	Ordered target-statistic permutations for categoricals.
early_stopping	False	Auto train/validation split; stop when val stops improving.
cat_combinations	False	Generate pairwise categorical combo features (helps all-cat datasets).

• Benchmark

• Reproduce the benchmark

python benchmarks/run_benchmarks.py --openml --seeds 5 --save
python benchmarks/make_tables.py benchmarks/results/<stamp>.json

Results land in benchmarks/results/<stamp>.txt (text log) and .json (raw per-seed metrics). Table PNG is written to images/. Competitors are auto-detected; install any of catboost, xgboost, lightgbm to see them.

• Pre-push hook (optional)

Run the test suite before every git push:

git config core.hooksPath .githooks