rohitg00/ai-engineering-from-scratch · error · PairingError

candidate and baseline lengths disagree

Error message

candidate and baseline lengths disagree

What it means

Error "candidate and baseline lengths disagree" thrown in rohitg00/ai-engineering-from-scratch.

Source

Thrown at phases/19-capstone-projects/53-result-evaluator/code/main.py:156

    bt = math.exp(log_bt)
    if x < (a + 1.0) / (a + b + 2.0):
        return bt * _lentz_betacf(a, b, x) / a
    return 1.0 - bt * _lentz_betacf(b, a, 1.0 - x) / b


def two_sided_t_p_value(t_stat: float, df: int) -> float:
    """Two sided p value for a t statistic with df degrees of freedom."""
    if df <= 0:
        return 1.0
    x = df / (df + t_stat * t_stat)
    p = regularised_incomplete_beta(df / 2.0, 0.5, x)
    return max(0.0, min(1.0, p))


def paired_t_test(candidate: list[float], baseline: list[float]) -> tuple[float, float | None, int]:
    """Return (mean_diff, p_value, n). p_value is None when n < 2."""
    if len(candidate) != len(baseline):
        raise PairingError("candidate and baseline lengths disagree")
    n = len(candidate)
    if n < 2:
        if n == 0:
            return 0.0, None, 0
        return float(candidate[0] - baseline[0]), None, n
    diffs = np.array(candidate) - np.array(baseline)
    mean_diff = float(diffs.mean())
    var_diff = float(diffs.var(ddof=1))
    if var_diff == 0.0:
        return mean_diff, (0.0 if mean_diff != 0.0 else 1.0), n
    t_stat = mean_diff / math.sqrt(var_diff / n)
    p = two_sided_t_p_value(t_stat, n - 1)
    return mean_diff, p, n


def _pair_by_seed(
    candidates: list[ExperimentResultLike],
    baselines: list[ExperimentResultLike],

View on GitHub (pinned to 39ea8a1c6d)

When it happens

Trigger: Thrown at phases/19-capstone-projects/53-result-evaluator/code/main.py:156 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of rohitg00/ai-engineering-from-scratch@39ea8a1c6d (2026-08-26). Data as JSON: /api/errors/8e4b66f734abaefa. Report an issue: GitHub.