Island-based gradient breaks: 85% reduction in barriers#87
Merged
NewGraphEnvironment merged 1 commit intomainfrom Apr 5, 2026
Merged
Island-based gradient breaks: 85% reduction in barriers#87NewGraphEnvironment merged 1 commit intomainfrom
NewGraphEnvironment merged 1 commit intomainfrom
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Replace interval-based gradient detection with vertex-based island approach adapted from bcfishpass. Computes gradient at every FWA vertex over a 100m upstream window, groups consecutive above-threshold vertices into islands, filters to islands >= 100m, returns one break at the entry of each island. Access barriers only (entry point = everything upstream blocked). Habitat classification uses segment attributes, not break presence. ADMS benchmarks: 15%: 28,960 → 4,229 barriers (85% reduction) 20%: 24,823 → 4,097 barriers (83% reduction) 25%: 21,295 → 3,824 barriers (82% reduction) Fixes locale-dependent numeric formatting (format() vs %s). Fixes #86 Relates to #83, #85 Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Summary
Replace interval-based gradient detection with vertex-based island approach (adapted from bcfishpass
gradient_barriers_load.sql):Entry-only breaks are correct for access barriers — everything upstream is blocked. Habitat classification uses segment attributes directly, not break presence.
Performance
Test plan
devtools::test()— 528 pass, 0 failFixes #86
Relates to #83, #85
Relates to NewGraphEnvironment/sred-2025-2026#16
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