{"abstract":"Ignored labels remain in the accuracy denominator.","category":"Evaluation metric aggregation","checks":6,"contract":"Return accuracy excluding positions whose true label equals ignore; no eligible positions yields 0.","contract_signature":"truth, pred, ignore","evaluation_group":"w3-eval-ignore-label-denominator","failed_approach":"Filtering out label zero also removes valid zero-class examples.","family":"w3-evaluation-metric-aggregation-ignore-label-denominator","id":"FA-100006","implementations":{"attempt":{"sha256":"db3581cbfea717e631780a67d4ebd583719b23b3431d1eef1b9565e500c391ba","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(truth, pred, ignore):\n    valid=[(a,b) for a,b in zip(truth,pred) if a!=ignore and a!=0]; return sum(a==b for a,b in valid)/len(valid) if valid else 0\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('ignored incorrect',solve([0,1,1],[1,1,0],0),.5)\ncheck('all ignored',solve([0]*N,[1]*N,0),0)\ncheck('zero is ordinary',solve([0,1],[0,0],9),.5)\ncheck('empty',solve([],[],0),0)\ncheck('all eligible correct',solve([N]*N,[N]*N,0),1)\ncheck('single eligible miss',solve([0,N],[1,N+1],0),0)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"broken":{"sha256":"5697c3e833e001f7d353c30adf564504feff7a0ca31bdfb2ee7c7cd6b8c531cb","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(truth, pred, ignore):\n    valid=[(a,b) for a,b in zip(truth,pred) if a!=ignore]; return sum(a==b for a,b in valid)/len(truth) if truth else 0\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('ignored incorrect',solve([0,1,1],[1,1,0],0),.5)\ncheck('all ignored',solve([0]*N,[1]*N,0),0)\ncheck('zero is ordinary',solve([0,1],[0,0],9),.5)\ncheck('empty',solve([],[],0),0)\ncheck('all eligible correct',solve([N]*N,[N]*N,0),1)\ncheck('single eligible miss',solve([0,N],[1,N+1],0),0)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"}},"limitations":"Inputs are finite toy labels and scores; this defines no benchmark protocol, production metric library, or model quality claim. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.","method":"Deterministic executable model with adversarial boundary fixtures.","provenance":{"created_by":"Failure Map","dependencies":"Python standard library","family":"w3-evaluation-metric-aggregation-ignore-label-denominator","generated_at":"2026-09-30T16:48:30.810537+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A small explicit evaluation contract makes aggregation behavior reproducible across labeled examples.","root_cause":"Ignored examples are removed from the numerator but still dilute the score.","sha256":"77de72af3ba75fa8af87a187015f4d8cfc0a189d4bd08225e4e9947b9f4e47c3","title":"Ignored labels remain in the accuracy denominator · case 01","variant":1,"variant_policy":"The fixture code references N, supplied as 1 through 5. Fixed boundary checks may repeat. These records share one mechanism and must remain together in evaluation splits.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":29.62,"exit_code":1,"observations":[{"actual":0.5,"check":"ignored incorrect","expected":0.5,"passed":true},{"actual":0,"check":"all ignored","expected":0,"passed":true},{"actual":0.0,"check":"zero is ordinary","expected":0.5,"passed":false},{"actual":0,"check":"empty","expected":0,"passed":true},{"actual":1.0,"check":"all eligible correct","expected":1,"passed":true},{"actual":0.0,"check":"single eligible miss","expected":0,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"ignored incorrect\", \"actual\": 0.5, \"expected\": 0.5, \"passed\": true}, {\"check\": \"all ignored\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"zero is ordinary\", \"actual\": 0.0, \"expected\": 0.5, \"passed\": false}, {\"check\": \"empty\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"all eligible correct\", \"actual\": 1.0, \"expected\": 1, \"passed\": true}, {\"check\": \"single eligible miss\", \"actual\": 0.0, \"expected\": 0, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":28.219,"exit_code":1,"observations":[{"actual":0.3333333333333333,"check":"ignored incorrect","expected":0.5,"passed":false},{"actual":0.0,"check":"all ignored","expected":0,"passed":true},{"actual":0.5,"check":"zero is ordinary","expected":0.5,"passed":true},{"actual":0,"check":"empty","expected":0,"passed":true},{"actual":1.0,"check":"all eligible correct","expected":1,"passed":true},{"actual":0.0,"check":"single eligible miss","expected":0,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"ignored incorrect\", \"actual\": 0.3333333333333333, \"expected\": 0.5, \"passed\": false}, {\"check\": \"all ignored\", \"actual\": 0.0, \"expected\": 0, \"passed\": true}, {\"check\": \"zero is ordinary\", \"actual\": 0.5, \"expected\": 0.5, \"passed\": true}, {\"check\": \"empty\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"all eligible correct\", \"actual\": 1.0, \"expected\": 1, \"passed\": true}, {\"check\": \"single eligible miss\", \"actual\": 0.0, \"expected\": 0, \"passed\": true}], \"passed\": false}\n"}},"member_only":{"stages":["fixed"],"fields":["implementations.fixed","verification.fixed","harness","repair"],"note":"The verified repair, its recorded checks, the repair description, and the scoring harness are available to members."}}