scripts/analyze_asr_errors.py

#!/usr/bin/env python3
from __future__ import annotations

import argparse
import csv
import json
import sys
from collections import Counter, defaultdict
from dataclasses import dataclass
from pathlib import Path
from typing import Iterable

sys.path.insert(0, str(Path(__file__).resolve().parents[1] / "src"))

from romani_asr.manifest import read_manifest_csv  # noqa: E402
from romani_asr.metrics import edit_distance  # noqa: E402
from romani_asr.text import has_non_latin_script, normalize_for_metric  # noqa: E402


DEFAULT_RUNS = [
    (
        "whisper_auto",
        Path("artifacts/evals/whisper-large-v3-turbo-zero-shot"),
    ),
    (
        "whisper_slovak",
        Path("artifacts/evals/whisper-large-v3-turbo-zero-shot-slovak-prompt"),
    ),
    (
        "whisper_romani_lora",
        Path("artifacts/evals/whisper-turbo-lora-romani-token-decoder-checkpoint-655"),
    ),
    (
        "whisper_romani_lora_guarded",
        Path("artifacts/evals/whisper-turbo-lora-romani-token-decoder-checkpoint-655-guarded"),
    ),
]


@dataclass(frozen=True)
class RunSpec:
    name: str
    path: Path


def parse_args() -> argparse.Namespace:
    parser = argparse.ArgumentParser(
        description="Analyze ASR predictions and write error-analysis artifacts."
    )
    parser.add_argument(
        "--manifest",
        type=Path,
        default=Path("artifacts/manifests/test.csv"),
    )
    parser.add_argument(
        "--run",
        action="append",
        default=[],
        help="Run spec in NAME=EVAL_DIR form. Defaults to measured Whisper runs.",
    )
    parser.add_argument(
        "--output-dir",
        type=Path,
        default=Path("artifacts/analysis/whisper-error-analysis"),
    )
    parser.add_argument(
        "--best-run",
        default="whisper_romani_lora_guarded",
        help="Run name to use for detailed cleanup and confusion analysis.",
    )
    parser.add_argument("--top-k", type=int, default=20)
    return parser.parse_args()


def parse_runs(values: list[str]) -> list[RunSpec]:
    if not values:
        return [RunSpec(name, path) for name, path in DEFAULT_RUNS if path.exists()]

    runs: list[RunSpec] = []
    for value in values:
        if "=" not in value:
            raise ValueError(f"--run must be NAME=EVAL_DIR, got: {value}")
        name, path_text = value.split("=", 1)
        if not name.strip():
            raise ValueError(f"--run name cannot be empty: {value}")
        runs.append(RunSpec(name.strip(), Path(path_text)))
    return runs


def read_predictions(eval_dir: Path) -> dict[str, dict[str, str]]:
    path = eval_dir / "predictions.csv"
    with path.open(newline="", encoding="utf-8") as handle:
        return {row["file_name"]: row for row in csv.DictReader(handle)}


def rate(reference: str, hypothesis: str, unit: str, keep_diacritics: bool) -> float:
    ref = normalize_for_metric(reference, keep_diacritics=keep_diacritics)
    hyp = normalize_for_metric(hypothesis, keep_diacritics=keep_diacritics)
    ref_units = ref.split() if unit == "word" else list(ref)
    hyp_units = hyp.split() if unit == "word" else list(hyp)
    if not ref_units:
        return 0.0
    return edit_distance(ref_units, hyp_units) / len(ref_units)


def corpus_rate(
    rows: list[dict[str, object]],
    run_name: str,
    unit: str,
    keep_diacritics: bool,
) -> float:
    total_errors = 0
    total_units = 0
    for row in rows:
        ref = normalize_for_metric(
            str(row["reference"]),
            keep_diacritics=keep_diacritics,
        )
        hyp = normalize_for_metric(
            str(row[f"{run_name}_prediction"]),
            keep_diacritics=keep_diacritics,
        )
        ref_units = ref.split() if unit == "word" else list(ref)
        hyp_units = hyp.split() if unit == "word" else list(hyp)
        total_errors += edit_distance(ref_units, hyp_units)
        total_units += len(ref_units)
    if total_units == 0:
        return 0.0
    return total_errors / total_units


def align(reference: list[str], hypothesis: list[str]) -> list[tuple[str, str, str]]:
    rows = len(reference) + 1
    cols = len(hypothesis) + 1
    costs = [[0] * cols for _ in range(rows)]
    back = [[""] * cols for _ in range(rows)]

    for i in range(1, rows):
        costs[i][0] = i
        back[i][0] = "del"
    for j in range(1, cols):
        costs[0][j] = j
        back[0][j] = "ins"

    for i, ref_item in enumerate(reference, start=1):
        for j, hyp_item in enumerate(hypothesis, start=1):
            candidates = [
                (costs[i - 1][j] + 1, "del"),
                (costs[i][j - 1] + 1, "ins"),
                (
                    costs[i - 1][j - 1] + (ref_item != hyp_item),
                    "eq" if ref_item == hyp_item else "sub",
                ),
            ]
            cost, op = min(candidates, key=lambda item: item[0])
            costs[i][j] = cost
            back[i][j] = op

    aligned: list[tuple[str, str, str]] = []
    i = len(reference)
    j = len(hypothesis)
    while i > 0 or j > 0:
        op = back[i][j]
        if op in {"eq", "sub"}:
            aligned.append((op, reference[i - 1], hypothesis[j - 1]))
            i -= 1
            j -= 1
        elif op == "del":
            aligned.append((op, reference[i - 1], ""))
            i -= 1
        elif op == "ins":
            aligned.append((op, "", hypothesis[j - 1]))
            j -= 1
        else:
            raise RuntimeError("Alignment backtrace failed")
    aligned.reverse()
    return aligned


def write_csv(path: Path, fieldnames: list[str], rows: Iterable[dict[str, object]]) -> None:
    path.parent.mkdir(parents=True, exist_ok=True)
    with path.open("w", newline="", encoding="utf-8") as handle:
        writer = csv.DictWriter(handle, fieldnames=fieldnames, extrasaction="ignore")
        writer.writeheader()
        writer.writerows(rows)


def fmt(value: float) -> str:
    return f"{value:.3f}"


def duration_bucket(duration_sec: float) -> str:
    if duration_sec < 1.0:
        return "<1s"
    if duration_sec < 2.0:
        return "1-2s"
    if duration_sec < 4.0:
        return "2-4s"
    return ">=4s"


def repetition_features(text: str) -> tuple[float, int]:
    normalized = normalize_for_metric(text)
    tokens = normalized.split()
    max_token_share = 0.0
    if tokens:
        token_counts = Counter(tokens)
        max_token_share = max(token_counts.values()) / len(tokens)

    longest_char_run = 0
    current_char = ""
    current_run = 0
    for ch in normalized:
        if ch == current_char:
            current_run += 1
        else:
            current_char = ch
            current_run = 1
        longest_char_run = max(longest_char_run, current_run)

    return max_token_share, longest_char_run


def average(values: Iterable[float]) -> float:
    values = list(values)
    if not values:
        return 0.0
    return sum(values) / len(values)


def main() -> None:
    args = parse_args()
    runs = parse_runs(args.run)
    if not runs:
        raise SystemExit("No eval runs found. Pass --run NAME=EVAL_DIR.")

    manifest_rows = read_manifest_csv(args.manifest)
    predictions = {run.name: read_predictions(run.path) for run in runs}
    missing = {
        run.name: [
            row["file_name"]
            for row in manifest_rows
            if row["file_name"] not in predictions[run.name]
        ]
        for run in runs
    }
    missing = {name: files for name, files in missing.items() if files}
    if missing:
        raise SystemExit(f"Prediction files are missing manifest rows: {missing}")

    per_utterance: list[dict[str, object]] = []
    for row in manifest_rows:
        file_name = row["file_name"]
        reference = row["transcript"]
        duration_sec = float(row["duration_sec"])
        out: dict[str, object] = {
            "file_name": file_name,
            "audio_path": row["audio_path"],
            "duration_sec": f"{duration_sec:.3f}",
            "duration_bucket": duration_bucket(duration_sec),
            "flag": row["flag"],
            "source_group": row["source_group"],
            "reference": reference,
            "reference_metric": normalize_for_metric(reference),
            "reference_word_count": len(normalize_for_metric(reference).split()),
            "reference_char_count": len(normalize_for_metric(reference)),
        }
        for run in runs:
            prediction = predictions[run.name][file_name]["prediction"]
            max_token_share, longest_char_run = repetition_features(prediction)
            out[f"{run.name}_prediction"] = prediction
            out[f"{run.name}_wer"] = rate(reference, prediction, "word", True)
            out[f"{run.name}_cer"] = rate(reference, prediction, "char", True)
            out[f"{run.name}_wer_ascii"] = rate(reference, prediction, "word", False)
            out[f"{run.name}_cer_ascii"] = rate(reference, prediction, "char", False)
            out[f"{run.name}_non_latin"] = has_non_latin_script(prediction)
            ref_chars = max(1, len(normalize_for_metric(reference)))
            hyp_chars = len(normalize_for_metric(prediction))
            out[f"{run.name}_char_ratio"] = hyp_chars / ref_chars
            out[f"{run.name}_max_token_share"] = max_token_share
            out[f"{run.name}_longest_char_run"] = longest_char_run
        per_utterance.append(out)

    run_summary: list[dict[str, object]] = []
    for run in runs:
        rows = per_utterance
        total_latency = sum(
            float(predictions[run.name][row["file_name"]].get("latency_sec", 0.0))
            for row in manifest_rows
        )
        run_summary.append(
            {
                "run": run.name,
                "path": str(run.path),
                "count": len(rows),
                "wer": corpus_rate(rows, run.name, "word", True),
                "cer": corpus_rate(rows, run.name, "char", True),
                "wer_ascii": corpus_rate(rows, run.name, "word", False),
                "cer_ascii": corpus_rate(rows, run.name, "char", False),
                "non_latin_outputs": sum(
                    bool(row[f"{run.name}_non_latin"]) for row in rows
                ),
                "exact_matches": sum(
                    float(row[f"{run.name}_wer"]) == 0.0 for row in rows
                ),
                "mean_latency_sec": total_latency / len(rows) if rows else 0.0,
                "total_latency_sec": total_latency,
            }
        )

    best_name = args.best_run if args.best_run in predictions else runs[-1].name
    baseline_name = (
        "whisper_slovak"
        if "whisper_slovak" in predictions and best_name != "whisper_slovak"
        else runs[0].name
    )

    detailed_rows: list[dict[str, object]] = []
    for row in per_utterance:
        best_cer = float(row[f"{best_name}_cer"])
        base_cer = float(row[f"{baseline_name}_cer"])
        best_wer = float(row[f"{best_name}_wer"])
        char_ratio = float(row[f"{best_name}_char_ratio"])
        reasons: list[str] = []
        if best_cer >= 0.25:
            reasons.append("high_cer")
        if best_wer >= 1.0:
            reasons.append("high_wer")
        if best_cer - base_cer >= 0.05:
            reasons.append("regression_vs_baseline")
        if char_ratio >= 1.5:
            reasons.append("over_generation")
        if char_ratio <= 0.6:
            reasons.append("under_generation")
        if (
            float(row[f"{best_name}_max_token_share"]) >= 0.4
            and len(str(row[f"{best_name}_prediction"]).split()) >= 8
        ) or int(row[f"{best_name}_longest_char_run"]) >= 20:
            reasons.append("repetition_loop")
        if bool(row[f"{best_name}_non_latin"]):
            reasons.append("non_latin_output")
        if reasons:
            detailed_rows.append(
                {
                    **row,
                    "review_reasons": ",".join(reasons),
                    "baseline_cer": base_cer,
                    "best_cer": best_cer,
                    "cer_delta_vs_baseline": best_cer - base_cer,
                }
            )

    detailed_rows.sort(
        key=lambda row: (
            float(row["best_cer"]),
            float(row["cer_delta_vs_baseline"]),
            float(row[f"{best_name}_wer"]),
        ),
        reverse=True,
    )

    char_confusions: Counter[tuple[str, str]] = Counter()
    word_confusions: Counter[tuple[str, str]] = Counter()
    for row in per_utterance:
        ref = normalize_for_metric(str(row["reference"]))
        hyp = normalize_for_metric(str(row[f"{best_name}_prediction"]))
        for op, ref_item, hyp_item in align(list(ref), list(hyp)):
            if op == "sub":
                char_confusions[(ref_item, hyp_item)] += 1
        for op, ref_item, hyp_item in align(ref.split(), hyp.split()):
            if op == "sub":
                word_confusions[(ref_item, hyp_item)] += 1

    bucket_rows: list[dict[str, object]] = []
    for group_key in ["duration_bucket", "flag", "source_group"]:
        grouped: dict[str, list[dict[str, object]]] = defaultdict(list)
        for row in per_utterance:
            grouped[str(row[group_key])].append(row)
        for value, rows in sorted(grouped.items()):
            bucket_rows.append(
                {
                    "group": group_key,
                    "value": value,
                    "count": len(rows),
                    f"{best_name}_wer": corpus_rate(rows, best_name, "word", True),
                    f"{best_name}_cer": corpus_rate(rows, best_name, "char", True),
                    f"{baseline_name}_wer": corpus_rate(
                        rows, baseline_name, "word", True
                    ),
                    f"{baseline_name}_cer": corpus_rate(
                        rows, baseline_name, "char", True
                    ),
                }
            )

    output_dir = args.output_dir
    output_dir.mkdir(parents=True, exist_ok=True)

    per_fields = [
        "file_name",
        "audio_path",
        "duration_sec",
        "duration_bucket",
        "flag",
        "source_group",
        "reference",
        "reference_metric",
        "reference_word_count",
        "reference_char_count",
    ]
    for run in runs:
        per_fields.extend(
            [
                f"{run.name}_prediction",
                f"{run.name}_wer",
                f"{run.name}_cer",
                f"{run.name}_wer_ascii",
                f"{run.name}_cer_ascii",
                f"{run.name}_non_latin",
                f"{run.name}_char_ratio",
                f"{run.name}_max_token_share",
                f"{run.name}_longest_char_run",
            ]
        )

    write_csv(output_dir / "per_utterance.csv", per_fields, per_utterance)
    write_csv(
        output_dir / "run_summary.csv",
        [
            "run",
            "path",
            "count",
            "wer",
            "cer",
            "wer_ascii",
            "cer_ascii",
            "non_latin_outputs",
            "exact_matches",
            "mean_latency_sec",
            "total_latency_sec",
        ],
        run_summary,
    )
    review_fields = [
        "file_name",
        "audio_path",
        "duration_sec",
        "flag",
        "source_group",
        "review_reasons",
        "reference",
    ]
    if baseline_name != best_name:
        review_fields.append(f"{baseline_name}_prediction")
    review_fields.extend(
        [
            f"{best_name}_prediction",
            "baseline_cer",
            "best_cer",
            "cer_delta_vs_baseline",
            f"{best_name}_wer",
            f"{best_name}_char_ratio",
            f"{best_name}_max_token_share",
            f"{best_name}_longest_char_run",
        ]
    )
    write_csv(output_dir / "review_candidates.csv", review_fields, detailed_rows)
    bucket_fields = ["group", "value", "count", f"{best_name}_wer", f"{best_name}_cer"]
    if baseline_name != best_name:
        bucket_fields.extend([f"{baseline_name}_wer", f"{baseline_name}_cer"])
    write_csv(output_dir / "bucket_summary.csv", bucket_fields, bucket_rows)
    write_csv(
        output_dir / "char_confusions.csv",
        ["reference_char", "prediction_char", "count"],
        (
            {
                "reference_char": ref_item,
                "prediction_char": hyp_item,
                "count": count,
            }
            for (ref_item, hyp_item), count in char_confusions.most_common()
        ),
    )
    write_csv(
        output_dir / "word_substitutions.csv",
        ["reference_word", "prediction_word", "count"],
        (
            {
                "reference_word": ref_item,
                "prediction_word": hyp_item,
                "count": count,
            }
            for (ref_item, hyp_item), count in word_confusions.most_common()
        ),
    )

    summary = {
        "manifest": str(args.manifest),
        "best_run": best_name,
        "baseline_run": baseline_name,
        "runs": run_summary,
        "review_candidate_count": len(detailed_rows),
        "outputs": {
            "per_utterance": str(output_dir / "per_utterance.csv"),
            "run_summary": str(output_dir / "run_summary.csv"),
            "review_candidates": str(output_dir / "review_candidates.csv"),
            "bucket_summary": str(output_dir / "bucket_summary.csv"),
            "char_confusions": str(output_dir / "char_confusions.csv"),
            "word_substitutions": str(output_dir / "word_substitutions.csv"),
        },
    }
    (output_dir / "summary.json").write_text(
        json.dumps(summary, indent=2, ensure_ascii=False),
        encoding="utf-8",
    )

    top_improvements = []
    top_regressions = []
    if baseline_name != best_name:
        top_improvements = sorted(
            per_utterance,
            key=lambda row: float(row[f"{baseline_name}_cer"])
            - float(row[f"{best_name}_cer"]),
            reverse=True,
        )[: args.top_k]
        top_regressions = sorted(
            per_utterance,
            key=lambda row: float(row[f"{best_name}_cer"])
            - float(row[f"{baseline_name}_cer"]),
            reverse=True,
        )[: args.top_k]

    lines = [
        "# ASR Error Analysis",
        "",
        f"Manifest: `{args.manifest}`",
        f"Best run for detailed analysis: `{best_name}`",
        f"Comparison baseline: `{baseline_name}`",
        "",
        "## Run Summary",
        "",
        "| Run | WER | CER | ASCII WER | ASCII CER | Exact | Non-Latin | Mean Latency |",
        "| --- | ---: | ---: | ---: | ---: | ---: | ---: | ---: |",
    ]
    for row in run_summary:
        lines.append(
            "| "
            f"{row['run']} | {fmt(float(row['wer']))} | "
            f"{fmt(float(row['cer']))} | {fmt(float(row['wer_ascii']))} | "
            f"{fmt(float(row['cer_ascii']))} | {row['exact_matches']} | "
            f"{row['non_latin_outputs']} | {fmt(float(row['mean_latency_sec']))}s |"
        )

    lines.extend(
        [
            "",
            "## What To Review First",
            "",
            f"- Review candidates: {len(detailed_rows)} clips",
            "- Prioritize rows marked `high_cer`, `regression_vs_baseline`, "
            "`over_generation`, `under_generation`, or `repetition_loop`.",
            "- Listen before editing labels; the CSV identifies likely problems, "
            "not guaranteed transcript mistakes.",
            "",
        ]
    )
    if baseline_name != best_name:
        lines.extend(["## Top Improvements", ""])
        for row in top_improvements[:10]:
            delta = float(row[f"{baseline_name}_cer"]) - float(row[f"{best_name}_cer"])
            lines.extend(
                [
                    f"### {row['file_name']} (+{fmt(delta)} CER)",
                    "",
                    f"- REF: {row['reference']}",
                    f"- {baseline_name}: {row[f'{baseline_name}_prediction']}",
                    f"- {best_name}: {row[f'{best_name}_prediction']}",
                    "",
                ]
            )

        lines.extend(["## Top Regressions", ""])
        for row in top_regressions[:10]:
            delta = float(row[f"{best_name}_cer"]) - float(
                row[f"{baseline_name}_cer"]
            )
            lines.extend(
                [
                    f"### {row['file_name']} (-{fmt(delta)} CER)",
                    "",
                    f"- REF: {row['reference']}",
                    f"- {baseline_name}: {row[f'{baseline_name}_prediction']}",
                    f"- {best_name}: {row[f'{best_name}_prediction']}",
                    "",
                ]
            )
    else:
        lines.extend(["## Worst Outputs", ""])
        for row in detailed_rows[:10]:
            lines.extend(
                [
                    f"### {row['file_name']} (CER {fmt(float(row['best_cer']))})",
                    "",
                    f"- Reasons: {row['review_reasons']}",
                    f"- REF: {row['reference']}",
                    f"- {best_name}: {row[f'{best_name}_prediction'][:500]}",
                    "",
                ]
            )

    lines.extend(
        [
            "## Common Character Substitutions",
            "",
            "| Reference | Prediction | Count |",
            "| --- | --- | ---: |",
        ]
    )
    for (ref_item, hyp_item), count in char_confusions.most_common(15):
        ref_label = ref_item if ref_item != " " else "`space`"
        hyp_label = hyp_item if hyp_item != " " else "`space`"
        lines.append(f"| {ref_label} | {hyp_label} | {count} |")

    lines.extend(
        [
            "",
            "## Output Files",
            "",
            "- `per_utterance.csv`: every prediction with per-clip WER/CER",
            "- `review_candidates.csv`: clips to listen to first",
            "- `bucket_summary.csv`: error by duration, flag, and source group",
            "- `char_confusions.csv`: best-run character substitutions",
            "- `word_substitutions.csv`: best-run word substitutions",
        ]
    )

    (output_dir / "summary.md").write_text("\n".join(lines) + "\n", encoding="utf-8")
    print(json.dumps(summary, indent=2, ensure_ascii=False), flush=True)


if __name__ == "__main__":
    main()