Speed up majority/threshold consensus to O(kn)#272
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Compute majority-rule and threshold `Consensus()` (and `SplitFrequency()`) by counting every split's frequency in a single pass and keeping those at or above the threshold, replacing the O(k^2 n) multi-reference comparison. Majority splits each occur in more than half the trees, so they are pairwise (hence globally) compatible and form a valid tree directly. Time is linear in the number of trees (~25x faster at k = 1600; scaling exponent 0.97 vs 1.91). The count defaults to 128-bit hashing (O(kn), exact with overwhelming probability); `exact = TRUE` selects a slower deterministic bitmask count. `Consensus()` and `SplitFrequency()` share one counting core. Strict consensus (p = 1) keeps its already-linear single-reference path. Cites Jansson, Shen & Sung (2016); implementation informed by their FACT package (whose majority-consensus code proved unusable on edge cases, so no FACT source is incorporated). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Codecov Report❌ Patch coverage is
Additional details and impacted files@@ Coverage Diff @@
## main #272 +/- ##
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+ Coverage 96.12% 96.19% +0.07%
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Files 81 81
Lines 6032 6039 +7
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+ Hits 5798 5809 +11
+ Misses 234 230 -4 ☔ View full report in Codecov by Sentry. 🚀 New features to boost your workflow:
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Performance benchmark results
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Compute majority-rule and threshold
Consensus()(andSplitFrequency()) by counting every split's frequency in a single pass and keeping those at or above the threshold, replacing the O(k^2 n) multi-reference comparison. Majority splits each occur in more than half the trees, so they are pairwise (hence globally) compatible and form a valid tree directly. Time is linear in the number of trees (~25x faster at k = 1600; scaling exponent 0.97 vs 1.91).The count defaults to 128-bit hashing (O(kn), exact with overwhelming probability);
exact = TRUEselects a slower deterministic bitmask count.Consensus()andSplitFrequency()share one counting core. Strict consensus (p = 1) keeps its already-linear single-reference path.Cites Jansson, Shen & Sung (2016); implementation informed by their FACT package (whose majority-consensus code proved unusable on edge cases, so no FACT source is incorporated).