FAQ

Why does Target.probability fail on my RandomForest? Forest classifiers average probabilities; there is no sigmoid link to invert. Their raw score is the averaged probability — use Target.raw(range=(0.0, 0.3)).

Why is my counterfactual Infeasible? The search exhausted its budget without a candidate satisfying the target and every constraint. Check for contradictory constraints (e.g. everything frozen), an unreachable target interval, or raise time_budget_s.

Can I run treecf where xgboost cannot be installed? Yes. Parsers accept JSON dumps (Booster.save_model("model.json"), dump_model(), CatBoost format="json"), and the genetic backend has no dependencies beyond the wheel itself: pip install treecf on the scoring host, ship the dump file.

What is the Rust core, and do I need a Rust toolchain? backend="genetic" runs a compiled Rust engine bundled inside the platform wheel (44–58× faster than the equivalent numpy implementation — see backends — performance). Installing from a wheel needs no toolchain; only building from the sdist compiles Rust. The engine is held to bitwise parity with Python on tree evaluation and constraint checking, and to statistical parity on end-to-end GA outcomes; every result is float-verified in Python before being returned.

When would I use backend="python"? It is the original numpy implementation of the same genetic algorithm, kept as a reference engine (and as the behavioral baseline the Rust core is tested against). Use it to cross-check results or in environments where the compiled extension cannot load; expect identical result quality, just slower.

Are mined constraints safe to apply automatically? No, by design. They are sample invariants, not domain truths; the API returns them for review (as_code()), and near-invariants are flagged as data-quality findings instead of constraints.

Do NaN flips count as "changes" for sparsity and diversity? Yes — flipping a value to NaN (or back) increments n_changed, pays the configured delta, and counts in distinct_changes diversity cuts.