Refactoring lab

games/frogger/__init__.py

@@ -0,0 +1,161 @@
+"""Frogger: guide a frog across busy traffic lanes to reach the far side.
+
+The frog starts at the bottom row. Cars move across the lanes between the
+start and goal. Each lane has cars moving at different speeds in alternating
+directions. The frog earns +10 for each row advanced, +50 for reaching the
+top row, and -10 for being hit by a car or falling off the edge. Episodes end
+when the frog reaches the top, gets hit, or energy runs out.
+"""
+
+from random import randint
+from retro.game import Game
+
+BOARD_WIDTH = 20
+BOARD_HEIGHT = 12
+NUM_LANES = BOARD_HEIGHT - 2
+START_ENERGY = 200
+
+
+class Frog:
+    name = "Frog"
+    character = 'O'
+    color = "green_on_black"
+    position = (0, 0)
+
+    UP = (0, -1)
+    DOWN = (0, 1)
+    LEFT = (-1, 0)
+    RIGHT = (1, 0)
+
+    def __init__(self):
+        self._direction = self.UP
+
+    def handle_keystroke(self, keystroke, game):
+        if keystroke.name == "KEY_UP":
+            self._direction = self.UP
+        elif keystroke.name == "KEY_DOWN":
+            self._direction = self.DOWN
+        elif keystroke.name == "KEY_LEFT":
+            self._direction = self.LEFT
+        elif keystroke.name == "KEY_RIGHT":
+            self._direction = self.RIGHT
+
+    def play_turn(self, game):
+        bw, bh = game.board_size
+        x, y = self.position
+        dx, dy = self._direction
+        nx, ny = x + dx, y + dy
+
+        if not (0 <= nx < bw):
+            game.state['reward'] -= 10
+            game.state['energy'] -= 50
+            self._reset(game)
+            return
+
+        if not (0 <= ny < bh):
+            if ny < 0:
+                game.state['score'] += 50
+                game.state['reward'] += 50
+            else:
+                game.state['reward'] -= 5
+            self._reset(game)
+            return
+
+        prev_y = y
+        self.position = (nx, ny)
+        game.state['energy'] -= 1
+        game.state['reward'] -= 0.01
+
+        if ny < prev_y:
+            advancement = prev_y - ny
+            game.state['score'] += advancement * 10
+            game.state['reward'] += advancement * 5
+
+        for agent in game.agents:
+            if hasattr(agent, '_is_car') and agent.position == self.position:
+                game.state['reward'] -= 10
+                game.state['energy'] -= 50
+                self._reset(game)
+                return
+
+        bw, bh = game.board_size
+        fx, fy = self.position
+        game.state['frog_x'] = fx / bw
+        game.state['frog_y'] = fy / bh
+
+        if game.state['energy'] <= 0:
+            game.end()
+
+    def _reset(self, game):
+        bw, bh = game.board_size
+        self.position = (bw // 2, bh - 1)
+        self._direction = self.UP
+        if game.state['energy'] <= 0:
+            game.end()
+
+
+class Car:
+    _is_car = True
+    character = 'X'
+    color = "red_on_black"
+
+    def __init__(self, lane, speed, direction, start_x, board_width):
+        self.name = f"Car {lane}_{start_x}"
+        self._lane = lane
+        self._speed = speed
+        self._direction = direction
+        self._board_width = board_width
+        self._step = 0
+        self.position = (start_x, lane)
+
+    def play_turn(self, game):
+        self._step += 1
+        if self._step < self._speed:
+            return
+        self._step = 0
+        x, y = self.position
+        x = (x + self._direction) % self._board_width
+        self.position = (x, y)
+
+        frog = game.get_agent_by_name("Frog")
+        if frog.position == self.position:
+            frog._reset(game)
+            game.state['reward'] -= 10
+            game.state['energy'] -= 50
+
+
+def create_game():
+    bw, bh = BOARD_WIDTH, BOARD_HEIGHT
+    frog = Frog()
+    frog.position = (bw // 2, bh - 1)
+
+    agents = [frog]
+    car_id = 0
+    for lane_idx, row in enumerate(range(1, bh - 1)):
+        direction = 1 if lane_idx % 2 == 0 else -1
+        speed = 2 + (lane_idx % 3)
+        num_cars = 2 + (lane_idx % 3)
+        spacing = bw // num_cars
+        for i in range(num_cars):
+            start_x = (i * spacing + lane_idx * 3) % bw
+            agents.append(Car(row, speed, direction, start_x, bw))
+            car_id += 1
+
+    game = Game(
+        agents,
+        {
+            'score': 0,
+            'reward': 0.0,
+            'energy': START_ENERGY,
+            'frog_x': (bw // 2) / bw,
+            'frog_y': (bh - 1) / bh,
+        },
+        board_size=(bw, bh),
+        framerate=8,
+        show_state=['score', 'energy'],
+    )
+    return game
+
+
+if __name__ == '__main__':
+    create_game().play()