code/_rev_linear_probe_matched_visual.py

"""
EXP REV-LP-MV: Linear probes on matched-visual conditions (R2 highest-value fix).

Adds linear-probe baselines to the gradient figure for:
  1. Velocity interpolation (matched visuals, kinematic split)
  2. Elastic vs inelastic restitution split (matched visuals, dynamics-class split)
  3. Standard-gravity vs low-gravity (matched visuals, dynamics shift)

Each is a logistic regression on l2-pooled V-JEPA 2 features at N in {16, 192}, 5 seeds.
"""
import json
import time
import os
from pathlib import Path
from datetime import datetime, timezone

import numpy as np
import torch
from sklearn.linear_model import LogisticRegression
from sklearn.preprocessing import StandardScaler

PROMPT_RECEIVED_TIME = datetime.now(timezone.utc).isoformat()
print(f"PROMPT_RECEIVED_TIME = {PROMPT_RECEIVED_TIME}", flush=True)
T0 = time.time()

OUT = Path("results/reviewer_response/exp_lp_matched_visual")
OUT.mkdir(parents=True, exist_ok=True)
N_LIST = [16, 192]
N_SEEDS = 5
RNG_BASE = 1234


def log(msg):
    ts = datetime.now(timezone.utc).strftime("%H:%M:%SZ")
    print(f"[{ts}] LP-MV: {msg}", flush=True)


def pool_l2(features_3d):
    """L2-pool features along temporal axis: (N, T, D) -> (N, D)."""
    f = features_3d
    if f.ndim == 3:
        return f.mean(dim=1).numpy()
    return f.numpy()


def stratified_subset(rng, y, n_per_class):
    """Indices of n_per_class examples per class."""
    idxs = []
    for c in np.unique(y):
        cand = np.where(y == c)[0]
        if len(cand) == 0:
            continue
        chosen = rng.choice(cand, size=min(n_per_class, len(cand)), replace=False)
        idxs.extend(chosen.tolist())
    return np.array(sorted(idxs))


def train_lp(X_tr, y_tr, X_te, y_te):
    sc = StandardScaler().fit(X_tr)
    Xs_tr = sc.transform(X_tr)
    Xs_te = sc.transform(X_te)
    model = LogisticRegression(max_iter=2000, C=1.0, multi_class="auto",
                               solver="lbfgs")
    model.fit(Xs_tr, y_tr)
    return float((model.predict(Xs_te) == y_te).mean())


def stats(vals):
    v = np.array(vals)
    return float(v.mean()), float(v.std(ddof=1) if len(v) > 1 else 0.0)


def run_split(name, X_src, y_src, X_tgt, y_tgt, n_classes):
    """Evaluate linear probe at N in N_LIST.

    Source-train-only baseline: train on full source, evaluate on target (N=0).
    N>0: train on full source + N stratified target examples, evaluate on remaining target.
    """
    log(f"=== {name}: src={X_src.shape}, tgt={X_tgt.shape}, n_classes={n_classes}")
    results = {"N0_source_only": [], "curve": {N: [] for N in N_LIST}}

    # N=0: train on source, evaluate on target
    for s in range(N_SEEDS):
        # Subsample source to be fair (use all of it; stratification not needed here)
        acc = train_lp(X_src, y_src, X_tgt, y_tgt)
        results["N0_source_only"].append(acc)
    log(f"  N=0 src-only: {stats(results['N0_source_only'])[0]:.3f} ± {stats(results['N0_source_only'])[1]:.3f}")

    # N=16,192: train on source + N stratified target, eval on remaining target
    smallest = min(int(np.sum(y_tgt == c)) for c in np.unique(y_tgt))
    for N in N_LIST:
        per_class = max(1, N // n_classes)
        # Clamp so we leave at least 30% of each target class for evaluation
        per_class = min(per_class, int(0.7 * smallest))
        for s in range(N_SEEDS):
            rng = np.random.default_rng(RNG_BASE + s)
            tgt_idx_train = stratified_subset(rng, y_tgt, per_class)
            mask = np.ones(len(y_tgt), bool); mask[tgt_idx_train] = False
            X_eval = X_tgt[mask]; y_eval = y_tgt[mask]
            if len(y_eval) == 0:
                continue
            X_tr = np.concatenate([X_src, X_tgt[tgt_idx_train]], axis=0)
            y_tr = np.concatenate([y_src, y_tgt[tgt_idx_train]], axis=0)
            acc = train_lp(X_tr, y_tr, X_eval, y_eval)
            results["curve"][N].append(acc)
        if results["curve"][N]:
            m, sd = stats(results["curve"][N])
            log(f"  N={N:>3d}: {m:.3f} ± {sd:.3f}  (per_class={per_class})")
        else:
            log(f"  N={N:>3d}: SKIPPED (insufficient target data)")
    return results


# ──────────────────────────────────────────────────────────────────
# Load standard collision features and labels
# ──────────────────────────────────────────────────────────────────
log("Loading standard collision features ...")
std_feat = torch.load(
    "results/acceptance_boost/exp2_cache/feat_vjepa2_collision_orig.pt",
    map_location="cpu", weights_only=False)["features"]
log(f"  std collision features: {tuple(std_feat.shape)}")

labels = np.load("results/kinematics_vs_mechanics/labels_collision.npz")
restitution_bin = labels["restitution_bin"]      # 600-d, 3 classes
mass_bin = labels["mass_bin"]                    # 600-d, 3 classes
velocity_pre_scalar = labels["velocity_pre_scalar"]
restitution_scalar = labels["restitution_scalar"]
log(f"  labels: restit_bin classes {sorted(set(restitution_bin))}, mass_bin classes {sorted(set(mass_bin))}")

X_std = pool_l2(std_feat)   # (600, 1024)
log(f"  X_std shape: {X_std.shape}")


# ──────────────────────────────────────────────────────────────────
# 1. Velocity interpolation (matched-visual kinematic split)
#    train on low-velocity half, eval on high-velocity half (predict restitution_bin)
# ──────────────────────────────────────────────────────────────────
log("=== Velocity interpolation split ===")
vmed = float(np.median(velocity_pre_scalar))
log(f"  velocity median = {vmed:.3f}")
mask_lo = velocity_pre_scalar < vmed
mask_hi = ~mask_lo

# direction A: train on lo, eval on hi
res_velocity_lo2hi = run_split(
    "velocity lo->hi",
    X_std[mask_lo], restitution_bin[mask_lo],
    X_std[mask_hi], restitution_bin[mask_hi],
    n_classes=3,
)
res_velocity_hi2lo = run_split(
    "velocity hi->lo",
    X_std[mask_hi], restitution_bin[mask_hi],
    X_std[mask_lo], restitution_bin[mask_lo],
    n_classes=3,
)


# ──────────────────────────────────────────────────────────────────
# 2. Elastic vs inelastic split (matched-visual dynamics-class split)
#    train on elastic (restit_scalar >= 0.5), eval on inelastic (predict mass_bin)
# ──────────────────────────────────────────────────────────────────
log("=== Elastic <-> inelastic split ===")
mask_elas = restitution_scalar >= 0.5
mask_inelas = ~mask_elas
log(f"  n elastic: {mask_elas.sum()}, n inelastic: {mask_inelas.sum()}")

res_elas2inelas = run_split(
    "elas->inelas",
    X_std[mask_elas], mass_bin[mask_elas],
    X_std[mask_inelas], mass_bin[mask_inelas],
    n_classes=3,
)
res_inelas2elas = run_split(
    "inelas->elas",
    X_std[mask_inelas], mass_bin[mask_inelas],
    X_std[mask_elas], mass_bin[mask_elas],
    n_classes=3,
)


# ──────────────────────────────────────────────────────────────────
# 3. Standard gravity <-> low gravity (matched-visual dynamics shift)
#    Need 75-scene std subset matching low-gravity (use seed-matched first 75 by RNG)
#    The exp_p1 setup matched RNG so std-grav and low-grav share per-scene physics
#    We use the first 75 scenes of std-grav (seed-aligned) as the matched set.
# ──────────────────────────────────────────────────────────────────
log("=== Std gravity <-> low gravity ===")
lg_path = "results/reviewer_response/exp_p1/feat_vjepa2_lowgrav.pt"
lg_feat = torch.load(lg_path, map_location="cpu", weights_only=False)["features"]
log(f"  low-grav features: {tuple(lg_feat.shape)}")
X_lg = pool_l2(lg_feat)

# Load low-grav labels from index.json
with open("kubric/output/collision_low_gravity_dataset/index.json") as fh:
    lg_idx = json.load(fh)
lg_restitution_scalar = np.array([s["restitution"] for s in lg_idx])
# Use Kubric union bins -- compute on std-grav restitution scalars
restit_bin_edges = np.percentile(restitution_scalar, [33.333, 66.667])
log(f"  union restit bin edges: {restit_bin_edges}")
def to_bin(scalar, edges):
    return np.searchsorted(edges, scalar)
y_lg_restit = to_bin(lg_restitution_scalar, restit_bin_edges).astype(np.int64)
y_std_restit = to_bin(restitution_scalar, restit_bin_edges).astype(np.int64)
log(f"  lg restit bin distribution: {np.bincount(y_lg_restit)}")
log(f"  std restit bin distribution: {np.bincount(y_std_restit)}")

# Use first 75 std-grav scenes (RNG-aligned to low-grav generation)
res_std2lg = run_split(
    "std->lg",
    X_std[:75], y_std_restit[:75],
    X_lg, y_lg_restit,
    n_classes=3,
)
res_lg2std = run_split(
    "lg->std",
    X_lg, y_lg_restit,
    X_std[:75], y_std_restit[:75],
    n_classes=3,
)


# ──────────────────────────────────────────────────────────────────
# Aggregate and save
# ──────────────────────────────────────────────────────────────────
def merge_dirs(a, b):
    """Average two directional results."""
    out = {"N0_source_only": [], "curve": {N: [] for N in N_LIST}}
    out["N0_source_only"] = a["N0_source_only"] + b["N0_source_only"]
    for N in N_LIST:
        out["curve"][N] = a["curve"][N] + b["curve"][N]
    return out


full = {
    "velocity_lo2hi": res_velocity_lo2hi,
    "velocity_hi2lo": res_velocity_hi2lo,
    "velocity_mean":  merge_dirs(res_velocity_lo2hi, res_velocity_hi2lo),
    "elas2inelas":    res_elas2inelas,
    "inelas2elas":    res_inelas2elas,
    "elastic_mean":   merge_dirs(res_elas2inelas, res_inelas2elas),
    "std2lg":         res_std2lg,
    "lg2std":         res_lg2std,
    "gravity_mean":   merge_dirs(res_std2lg, res_lg2std),
}

# Pretty summary
SUMMARY = ["EXP REV-LP-MV -- linear probes on matched-visual conditions (5 seeds, predict restitution/mass)",
           "",
           f"{'Condition':<30s} | {'N=0 (src-only)':>18s} | {'N=16':>14s} | {'N=192':>14s}",
           "-" * 86]
for name, r in full.items():
    if "_mean" not in name and not name in ("std2lg", "lg2std", "elas2inelas", "inelas2elas"):
        continue
    n0_m, n0_s = stats(r["N0_source_only"])
    n16_m, n16_s = stats(r["curve"][16])
    n192_m, n192_s = stats(r["curve"][192])
    SUMMARY.append(f"{name:<30s} | {n0_m*100:>5.1f}% +/- {n0_s*100:>4.1f}% | {n16_m*100:>5.1f}% +/- {n16_s*100:>4.1f}% | {n192_m*100:>5.1f}% +/- {n192_s*100:>4.1f}%")

print("\n".join(SUMMARY), flush=True)
with open(OUT / "exp_lp_matched_visual_summary.txt", "w") as fh:
    fh.write("\n".join(SUMMARY) + "\n")
with open(OUT / "exp_lp_matched_visual_summary.json", "w") as fh:
    json.dump(full, fh, indent=2)

end_ts = datetime.now(timezone.utc).isoformat()
runtime_min = (time.time() - T0) / 60.0
print(f"\nEND_TIME = {end_ts}", flush=True)
print(f"Total runtime: {runtime_min:.2f} min", flush=True)