Put near

PutNear (issue #178): a single room scattered with n_objects Key/Ball/Box instances; two distinct ones are chosen as the per-episode "move" (State.mission[0] - the object to carry) and "target" (State.mission[1] - the object to drop near) objects. The agent must pick up the move object and drop it within Chebyshev distance 1 of the target. Verified against MiniGrid's actual PutNearEnv.step: picking up the wrong object ends the episode immediately (0 reward); any genuine drop attempt (was holding something) also ends the episode, success determined by whether it landed near the target.

Each object's type is drawn independently (matching MiniGrid's own types = ["key", "ball", "box"] sampled per object, checked directly against source) - see go_to_object.py's module docstring for the padding-sentinel implementation this shares.

Registers with transitions_fn=transitions.deterministic_transition - see go_to_object.py's module docstring for why (the default stochastic_transition would otherwise walk every Ball entity a random step each turn, which real MiniGrid's Ball doesn't do outside DynamicObstacles).

PutNear

Bases: Environment

Navix-PutNear-*. A room scattered with n_objects coloured Key/Ball/Box objects; two are named in State.mission - one to carry (mission[0]) and one to drop it next to (mission[1]). Success: pick up the carry object and drop it within Chebyshev distance 1 of the target. Picking up the wrong object, or any drop attempt, ends the episode (reward 1 only on a correct near-drop).

Attributes:

Name	Type	Description
n_objects	int	how many objects to scatter.