def extract_traj(fname: str, config: dict) -> Trajectory:
"""Extract trajector from filename and create Trajectory instance.
Args:
fname: Filename from which to load trajectory.
config: Dictionary containing parameters of javascript simulation.
Returns:
Trajectory with mapped states and actions.
"""
states, actions = [], []
data = load_json(fname)
for step in data:
states.append(step['data']['state'])
actions.append(step['data']['action'])
traj = Trajectory(states, actions, config, fname)
traj.remap_states()
traj.as_numpy()
return traj
