Interpretable clinical models need stable feature subsets: the selected predictors should not change much when the data changes slightly. With very few outcome events per variable, this is hard to achieve. l0l2learn selects feature subsets for logistic regression under an explicit cardinality or budget constraint, solved as a mixed-integer conic optimization problem, instead of relying on Lasso-style penalties.
It provides two estimators:
L0L2Classifier: L0-constrained, L2-regularized logistic regressionResampledL0L2Classifier: the same with resampling and frequency-based aggregation for more stable selections, as proposed in our paper
from l0l2learn import ResampledL0L2Classifier
clf = ResampledL0L2Classifier(b=3, param_grid={"lambd": [1.0]}, n_resamples=3)
clf.fit(X_train, y_train)
clf.support_ # selected features
Install it with pip install l0l2learn. The conic solver needs a MOSEK license. The package is released under the MIT license.










