edbf76071e
The egocentric/egocentric_player/egocentric_radius flags were removed from retro_gamer in favor of an explicit observation_function. snake_observation.py reproduces the old egocentric+board+extras behavior by calling egocentric_board/encode_board/encode_state directly, and runs/snake/config.toml now points at it. That config change made the prior 12,000-episode checkpoint history incompatible (retro_gamer's checkpoint compatibility checker can't verify a new observation_function is behaviorally equivalent to the old flags, so it conservatively refuses to resume), so the old checkpoints were deleted and a fresh 20,000-episode run was recorded. Track only the four checkpoints the lab actually references (ep_1300, ep_2300, ep_4000, ep_20000) instead of all 200, and update .gitignore so future student runs of runs/snake aren't committed by default. snake_training.md's Q5 training-curve table and Q6 checkpoint episodes are updated to match the real numbers from this run.
32 lines
1.2 KiB
Python
32 lines
1.2 KiB
Python
"""A custom observation_function for retro.examples.snake.
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Crops the board to a window centered on the snake's head before encoding,
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using egocentric_board()/encode_board() from retro_gamer.observation as
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building blocks. This replaces retro_gamer's old built-in egocentric flags —
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cropping is now just something an observation_function does for itself.
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Point a run's config.toml at this with:
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[metadata]
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observation_function = "snake_observation:egocentric_observation"
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board_size = [17, 17] # must match RADIUS below: 2*8+1 = 17
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"""
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import numpy as np
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from retro.views.headless import HeadlessView
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from retro_gamer.observation import egocentric_board, encode_board, encode_state
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CHARACTER_SET = ["@", "*", ">", "<", "^", "v"]
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RADIUS = 8
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def egocentric_observation(game):
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"""Board cropped to a (2*RADIUS+1)^2 window around the snake's head, plus apple_dx/apple_dy."""
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view = HeadlessView()
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view.on_game_start(game)
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view.render(game)
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head = game.get_agent_by_name("Snake head")
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cropped = egocentric_board(view.board_characters, head.position, RADIUS)
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board_vec = encode_board(cropped, CHARACTER_SET).flatten()
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extras = encode_state(game.state, ["apple_dx", "apple_dy"])
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return np.concatenate([board_vec, extras])
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