Files
hvm-docs/eval/pvalue.py
T

157 lines
5.0 KiB
Python

"""Paired permutation test between two eval JSONL sidecars.
Compares per-query scores from two `eval.run_eval` sidecar files so
"P@1 went 0.88 → 0.91 on 25 queries" is not treated as a win.
python -m eval.pvalue \\
--a eval/results/baseline.jsonl \\
--b eval/results/new.jsonl \\
--metric rr
Exit 0 even when the difference is not significant — this is a report,
not a gate. No third-party deps; `random.Random(seed)` is enough.
"""
from __future__ import annotations
import argparse
import json
import random
from pathlib import Path
def load_sidecar(path: Path) -> list[dict]:
rows: list[dict] = []
with open(path) as fh:
for line in fh:
line = line.strip()
if line:
rows.append(json.loads(line))
return rows
def paired_permutation(
a: list[float],
b: list[float],
n_resamples: int = 10000,
seed: int = 0,
) -> dict:
"""Two-sided paired permutation test on per-query scores.
Null: each pair is exchangeable (randomly flipping the sign of
A_i - B_i). p_value is the fraction of permutations whose
|mean diff| is at least as large as the observed |mean(A-B)|.
"""
if len(a) != len(b):
raise ValueError(f"paired lengths differ: {len(a)} vs {len(b)}")
if not a:
raise ValueError("no paired queries to compare")
diffs = [x - y for x, y in zip(a, b)]
n = len(diffs)
observed = sum(diffs) / n
abs_obs = abs(observed)
rng = random.Random(seed)
extreme = 0
for _ in range(n_resamples):
total = 0.0
for d in diffs:
total += d if rng.random() < 0.5 else -d
if abs(total / n) >= abs_obs - 1e-15:
extreme += 1
p_value = extreme / n_resamples
return {
"A_mean": sum(a) / n,
"B_mean": sum(b) / n,
"Diff(A-B)": observed,
"p_value": p_value,
"significant": p_value < 0.05,
"n": n,
"n_resamples": n_resamples,
}
def _index(rows: list[dict], metric: str) -> dict[tuple[str, str], float]:
"""Map (retriever, query) -> score."""
out: dict[tuple[str, str], float] = {}
for row in rows:
retriever = str(row.get("retriever") or "")
query = str(row.get("query") or "")
if metric == "p_at_1":
score = float(row.get("p_at_1") or 0)
else:
score = float(row.get("rr") or 0)
out[(retriever, query)] = score
return out
def compare(
rows_a: list[dict],
rows_b: list[dict],
metric: str = "rr",
retriever: str | None = None,
n_resamples: int = 10000,
seed: int = 0,
) -> list[dict]:
"""Join on (retriever, query). One result dict per shared retriever."""
ia, ib = _index(rows_a, metric), _index(rows_b, metric)
retrievers = sorted({r for r, _ in ia} & {r for r, _ in ib})
if retriever:
retrievers = [r for r in retrievers if r == retriever]
if not retrievers:
raise ValueError(f"retriever {retriever!r} not in both sidecars")
reports = []
for name in retrievers:
queries = sorted({q for r, q in ia if r == name} & {q for r, q in ib if r == name})
if not queries:
continue
a_scores = [ia[(name, q)] for q in queries]
b_scores = [ib[(name, q)] for q in queries]
report = paired_permutation(a_scores, b_scores, n_resamples=n_resamples, seed=seed)
report["retriever"] = name
report["metric"] = metric
reports.append(report)
if not reports:
raise ValueError("no overlapping (retriever, query) pairs")
return reports
def render(reports: list[dict]) -> str:
lines = ["# Permutation test", ""]
for r in reports:
sig = "yes" if r["significant"] else "no"
lines += [
f"## `{r['retriever']}` ({r['metric']}, n={r['n']})",
"",
f"- A_mean: `{r['A_mean']:.4f}`",
f"- B_mean: `{r['B_mean']:.4f}`",
f"- Diff(A-B): `{r['Diff(A-B)']:.4f}`",
f"- p_value: `{r['p_value']:.4f}` ({r['n_resamples']} resamples)",
f"- significant (p < 0.05): **{sig}**",
"",
]
return "\n".join(lines)
def main() -> int:
p = argparse.ArgumentParser(description="Paired permutation test on two eval JSONL sidecars.")
p.add_argument("--a", type=Path, required=True, help="sidecar JSONL (system A)")
p.add_argument("--b", type=Path, required=True, help="sidecar JSONL (system B)")
p.add_argument("--metric", choices=("rr", "p_at_1"), default="rr")
p.add_argument("--retriever", default=None, help="restrict to one retriever name")
p.add_argument("--n-resamples", type=int, default=10000)
p.add_argument("--seed", type=int, default=0)
args = p.parse_args()
reports = compare(
load_sidecar(args.a),
load_sidecar(args.b),
metric=args.metric,
retriever=args.retriever,
n_resamples=args.n_resamples,
seed=args.seed,
)
print(render(reports), end="")
return 0
if __name__ == "__main__":
raise SystemExit(main())