Checkpoint 2

tools/collect_demos.py

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+"""Collect (obs, action) demonstrations from the sequential teacher.
+
+Runs the sequential algorithm across a grid of (n_sheep, seed) combos
+at full difficulty, logs the (observation, action) pair every Nth step,
+and saves successful trajectories to a numpy ``.npz`` for behavior
+cloning. Failed trajectories are dropped by default — we only want to
+teach the policy from good examples.
+
+Usage::
+
+    python -m tools.collect_demos --out training/demos.npz
+"""
+
+from __future__ import annotations
+
+import argparse
+import os
+import sys
+import time
+from pathlib import Path
+
+_HERE = os.path.dirname(os.path.abspath(__file__))
+_PROJECT_ROOT = os.path.normpath(os.path.join(_HERE, ".."))
+if _PROJECT_ROOT not in sys.path:
+    sys.path.insert(0, _PROJECT_ROOT)
+
+import numpy as np
+
+from herding.geometry import PEN_ENTRY
+from herding.sequential import compute_action
+from training.herding_env import HerdingEnv
+
+
+def collect_one(n_sheep: int, seed: int, max_steps: int, subsample: int):
+    env = HerdingEnv(n_sheep=n_sheep, max_steps=max_steps,
+                    difficulty=1.0, seed=seed)
+    obs, _ = env.reset(seed=seed)
+    obs_list, action_list = [], []
+    for step in range(max_steps):
+        positions = {f"s{i}": (float(env.sheep_x[i]), float(env.sheep_y[i]))
+                     for i in range(env.n_sheep) if not env.sheep_penned[i]}
+        if not positions:
+            break
+        vx, vy, _mode = compute_action(
+            (env.dog_x, env.dog_y), positions, PEN_ENTRY,
+        )
+        action = np.array([vx, vy], dtype=np.float32)
+        if step % subsample == 0:
+            obs_list.append(obs.copy())
+            action_list.append(action.copy())
+        obs, _r, term, trunc, _info = env.step(action)
+        if term or trunc:
+            break
+    success = bool(env.sheep_penned.all())
+    return (
+        np.asarray(obs_list, dtype=np.float32),
+        np.asarray(action_list, dtype=np.float32),
+        success,
+        env.steps,
+    )
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--out", default="training/demos.npz")
+    parser.add_argument("--n-sheep-list", default="1,2,3,5,8,10")
+    parser.add_argument("--seeds-per-n", type=int, default=15)
+    parser.add_argument("--max-steps", type=int, default=30000)
+    parser.add_argument("--subsample", type=int, default=5,
+                        help="Keep every Nth (obs, action) pair.")
+    parser.add_argument("--keep-failures", action="store_true",
+                        help="Include partial-success trajectories. Default off.")
+    args = parser.parse_args()
+
+    n_sheep_list = [int(x) for x in args.n_sheep_list.split(",")]
+    print(f"[demos] grid: n_sheep={n_sheep_list}, seeds={args.seeds_per_n}, "
+          f"max_steps={args.max_steps}, subsample={args.subsample}")
+
+    all_obs, all_actions, all_meta = [], [], []
+    t_start = time.time()
+    n_success = 0; n_total = 0
+
+    for n in n_sheep_list:
+        for seed in range(args.seeds_per_n):
+            obs, actions, success, total_steps = collect_one(
+                n, seed, args.max_steps, args.subsample,
+            )
+            n_total += 1
+            if success:
+                n_success += 1
+            keep = success or args.keep_failures
+            if keep and len(obs) > 0:
+                all_obs.append(obs)
+                all_actions.append(actions)
+                all_meta.append((n, seed, len(obs), int(success), total_steps))
+            tag = "✓" if success else "✗"
+            print(f"  [{tag}] n={n:>2d} seed={seed:>2d}  steps={total_steps:>6d}  "
+                  f"logged={len(obs):>5d}")
+
+    if not all_obs:
+        raise RuntimeError("No trajectories kept — try --keep-failures.")
+
+    obs = np.concatenate(all_obs, axis=0)
+    actions = np.concatenate(all_actions, axis=0)
+    meta = np.array(all_meta, dtype=np.int32)
+
+    Path(args.out).parent.mkdir(parents=True, exist_ok=True)
+    np.savez(args.out, obs=obs, actions=actions, meta=meta)
+
+    elapsed = time.time() - t_start
+    print(f"\n=== {n_success}/{n_total} trajectories successful ({100*n_success/n_total:.0f}%) ===")
+    print(f"=== {len(obs)} transitions saved to {args.out} ===")
+    print(f"=== obs={obs.shape}, actions={actions.shape}, elapsed={elapsed:.0f}s ===")
+
+
+if __name__ == "__main__":
+    main()