example_scripts/01_lane_changes.py

"""
Lane Change Analysis — Automatum Data Highway Area Pools (Multi-Drone)
Analyzes lane change behavior across all vehicles in a recording.

Usage:
    python 01_lane_changes.py <path_to_recording_folder>

Example:
    python 01_lane_changes.py ../Sample_Data/Pool-Highway-A9-OffenbauRastanlage_c025-c02598c7-fa60-4302-8cee-12a05f4e0db6

Note:
    The exports of this release do not contain the per-sample lane assignment
    (`lane_id_vec`). If it is missing, the script estimates lanes from the
    vehicle's lateral position across the road: per driving direction a local road
    axis (median lateral position in 20 m slices) is computed, the lateral offsets are
    clustered into lanes (histogram peaks), and a lane change is counted when
    a vehicle stays at least 1 s on a new lane.
"""
import sys
import os
import numpy as np
from openautomatumdronedata.dataset import droneDataset


def _road_axis(dynWorld):
    """Principal axis of all positions (unit vector) and the centroid."""
    pts = np.vstack([np.column_stack([o.x_vec, o.y_vec]) for o in dynWorld.dynamicObjects.values()
                     if len(o.x_vec) > 1])
    c = pts.mean(0)
    _, _, vt = np.linalg.svd(pts[::50] - c, full_matrices=False)
    return c, vt[0]


def estimate_lane_ids(dynWorld, lane_min_gap_m=2.5, min_dwell_s=1.0):
    """Estimated lane index per sample for every object (dict UUID -> np.array)."""
    c, ax = _road_axis(dynWorld)
    nrm = np.array([-ax[1], ax[0]])
    objs = [o for o in dynWorld.dynamicObjects.values() if len(o.x_vec) > 1]
    s, d, direction = {}, {}, {}
    for o in objs:
        p = np.column_stack([o.x_vec, o.y_vec]) - c
        s[o.UUID], d[o.UUID] = p @ ax, p @ nrm
        direction[o.UUID] = 1 if s[o.UUID][-1] >= s[o.UUID][0] else -1
    lane_ids = {}
    dt = dynWorld.delta_t
    for dirn in (1, -1):
        ids = [u for u in s if direction[u] == dirn]
        if not ids:
            continue
        S = np.concatenate([s[u] for u in ids]); D = np.concatenate([d[u] for u in ids])
        # local road axis of this direction: median lateral position in 20 m slices along the road
        edges_s = np.arange(S.min(), S.max() + 20.0, 20.0)
        idx = np.clip(np.digitize(S, edges_s) - 1, 0, len(edges_s) - 2)
        med = np.array([np.median(D[idx == k]) if np.any(idx == k) else np.nan for k in range(len(edges_s) - 1)])
        mid = 0.5 * (edges_s[1:] + edges_s[:-1]); ok = ~np.isnan(med)
        res = {u: d[u] - np.interp(s[u], mid[ok], med[ok]) for u in ids}
        R = np.concatenate(list(res.values()))
        hist, edges = np.histogram(R, bins=np.arange(R.min() - 1, R.max() + 1, 0.25))
        hist = np.convolve(hist, np.ones(5) / 5, mode="same")
        centers = 0.5 * (edges[1:] + edges[:-1])
        peaks = [i for i in range(1, len(hist) - 1)
                 if hist[i] >= hist[i - 1] and hist[i] > hist[i + 1] and hist[i] > 0.02 * hist.max()]
        lanes = []
        for i in sorted(peaks, key=lambda i: -hist[i]):
            if all(abs(centers[i] - l) > lane_min_gap_m for l in lanes):
                lanes.append(centers[i])
        lanes = np.sort(np.array(lanes))
        min_len = max(1, int(round(min_dwell_s / dt)))
        for u in ids:
            raw = np.argmin(np.abs(res[u][:, None] - lanes[None, :]), axis=1)
            # hysteresis: only accept a new lane after min_dwell_s on it
            out = raw.copy(); cur = raw[0]; run_start = 0
            for k in range(1, len(raw)):
                if raw[k] != raw[k - 1]:
                    run_start = k
                if raw[k] != cur and k - run_start + 1 >= min_len:
                    cur = raw[k]
                out[k] = cur
            lane_ids[u] = out
    return lane_ids


def analyze_lane_changes(dataset_path):
    print(f"Loading dataset from: {dataset_path}")
    dataset = droneDataset(dataset_path)
    dynWorld = dataset.dynWorld

    print(f"Vehicles found: {len(dynWorld)}")

    have_lane_ids = any(getattr(o, "lane_id_vec", None) is not None and len(o.lane_id_vec) > 0
                        for o in dynWorld.dynamicObjects.values())
    estimated = None
    if not have_lane_ids:
        print("lane_id_vec is not part of this export -> estimating lanes from the lateral position")
        estimated = estimate_lane_ids(dynWorld)

    lane_change_counts = []

    for dynObj in dynWorld.dynamicObjects.values():
        lane_ids = dynObj.lane_id_vec if have_lane_ids else estimated.get(dynObj.UUID)
        if lane_ids is None or len(lane_ids) == 0:
            continue

        changes = 0
        current_lane = lane_ids[0]
        for lane in lane_ids[1:]:
            if lane != current_lane:
                changes += 1
                current_lane = lane

        lane_change_counts.append({
            "uuid": dynObj.UUID,
            "type": dynObj.type,
            "changes": changes,
        })

    sorted_by_changes = sorted(lane_change_counts, key=lambda x: x["changes"], reverse=True)
    n_changing = sum(1 for x in lane_change_counts if x["changes"] > 0)
    total = sum(x["changes"] for x in lane_change_counts)
    print(f"Lane changes: {total} in total, {n_changing} of {len(lane_change_counts)} vehicles change lane at least once")

    print("\n--- Top 10 vehicles with most lane changes ---")
    for idx, item in enumerate(sorted_by_changes[:10]):
        print(f"{idx+1}. Vehicle {item['uuid']} ({item['type']}): {item['changes']} lane changes")


if __name__ == "__main__":
    if len(sys.argv) < 2:
        print("Usage: python 01_lane_changes.py <path_to_recording_folder>")
    else:
        analyze_lane_changes(sys.argv[1])