fix: select_n_components respects xprobe_fraction for prms/cost - #123
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jc-macdonald merged 1 commit intoAug 25, 2026
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_ensure_metric_opts auto-generates a held-out probe set whenever the caller hasn't supplied an explicit xprobe array, but it only checked for that array -- never the caller's own xprobe_fraction -- so it always fell back to a hardcoded 10% probe fraction regardless of what was configured (e.g. via recommend_config()). This affected both the "prms" and "cost" metrics equally, since the function doesn't gate on cfg.metric at all. Found while investigating a pp-eigentest trade-study result comparing cost vs prms for VBPCA-based rank selection (yoavram-lab/pp-eigentest#21).
jc-macdonald
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fix/122-xprobe-fraction-ignored-in-metric-opts
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August 25, 2026 13:47
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Closes #122.
Summary
_ensure_metric_opts(used internally byselect_n_componentsto auto-generate a held-out probe set for theprms/costmetrics) only checked whether an explicitxprobearray was supplied -- never the caller's ownxprobe_fraction. It always fell back to a hardcoded 10% probe fraction, silently discarding a tunedxprobe_fraction(e.g. fromrecommend_config()). Affects both"prms"and"cost"equally, since the function doesn't gate oncfg.metric.fit_opts["xprobe_fraction"]when it's a positive value, falling back to the historical 10% default only when unset/zero -- same behavior as before for anyone not passingxprobe_fraction.Test plan
_ensure_metric_opts: respects a configuredxprobe_fraction, and falls back to the 10% default when unset.ruff format --preview --check/ruff check --preview-- cleanmypy --strict src-- cleanpytest -q -m "not perf and not octave"-- 496 passed (0 regressions)