{"record":{"id":"e390570f18e3a6da","repo":"rohitg00/ai-engineering-from-scratch","slug":"n-must-be-positive","errorCode":null,"errorMessage":"n must be positive","messagePattern":"n must be positive","errorType":"validation","errorClass":"ValueError","httpStatus":null,"severity":"error","filePath":"phases/19-capstone-projects/71-classical-metrics/code/main.py","lineNumber":57,"sourceCode":"    pred_tokens = tokenize(prediction)\n    tgt_tokens = tokenize(target)\n    if not pred_tokens and not tgt_tokens:\n        return 1.0\n    if not pred_tokens or not tgt_tokens:\n        return 0.0\n    pred_counts = Counter(pred_tokens)\n    tgt_counts = Counter(tgt_tokens)\n    overlap = sum((pred_counts & tgt_counts).values())\n    if overlap == 0:\n        return 0.0\n    precision = overlap / sum(pred_counts.values())\n    recall = overlap / sum(tgt_counts.values())\n    return 2.0 * precision * recall / (precision + recall)\n\n\ndef _ngram_counts(tokens: list[str], n: int) -> Counter:\n    if n <= 0:\n        raise ValueError(\"n must be positive\")\n    if len(tokens) < n:\n        return Counter()\n    return Counter(tuple(tokens[i:i + n]) for i in range(len(tokens) - n + 1))\n\n\ndef _modified_precision(cand_tokens: list[str], ref_tokens: list[str], n: int) -> tuple[int, int]:\n    cand_ngrams = _ngram_counts(cand_tokens, n)\n    if not cand_ngrams:\n        return (0, 0)\n    ref_ngrams = _ngram_counts(ref_tokens, n)\n    clipped = 0\n    for gram, count in cand_ngrams.items():\n        clipped += min(count, ref_ngrams.get(gram, 0))\n    total = sum(cand_ngrams.values())\n    return (clipped, total)\n\n\ndef _brevity_penalty(cand_len: int, ref_len: int) -> float:","sourceCodeStart":39,"sourceCodeEnd":75,"githubUrl":"https://github.com/rohitg00/ai-engineering-from-scratch/blob/39ea8a1c6d0b61f071226eff7ede4d4105fed820/phases/19-capstone-projects/71-classical-metrics/code/main.py#L39-L75","documentation":"Error \"n must be positive\" thrown in rohitg00/ai-engineering-from-scratch.","triggerScenarios":"Thrown at phases/19-capstone-projects/71-classical-metrics/code/main.py:57 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":[],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"39ea8a1c6d0b61f071226eff7ede4d4105fed820","analyzedAt":"2026-08-26T03:13:46.626Z","schemaVersion":2},"datasetVersion":"2026-08-26T07:17:17.940Z"}