[fix] Non heuristic moves...

rl/game.py

@@ -0,0 +1,102 @@
+"""Connect Four game environment for self-play training."""
+
+import numpy as np
+
+ROWS = 6
+COLS = 7
+WIN_LENGTH = 4
+
+
+class ConnectFour:
+    """Connect Four game with numpy board representation.
+
+    Board encoding: 0 = empty, 1 = player 1, -1 = player 2.
+    """
+
+    def __init__(self):
+        self.reset()
+
+    def reset(self):
+        self.board = np.zeros((ROWS, COLS), dtype=np.int8)
+        self.current_player = 1
+        self.done = False
+        self.winner = 0  # 0 = no winner / draw, 1 or -1
+        self.move_count = 0
+        return self.get_state()
+
+    def get_state(self):
+        """Return board from current player's perspective as (6,7,2) tensor.
+
+        Channel 0: current player's pieces (1s).
+        Channel 1: opponent's pieces (1s).
+        """
+        state = np.zeros((ROWS, COLS, 2), dtype=np.float32)
+        state[:, :, 0] = (self.board == self.current_player).astype(np.float32)
+        state[:, :, 1] = (self.board == -self.current_player).astype(np.float32)
+        return state
+
+    def legal_moves(self):
+        """Return list of columns that are not full."""
+        return [c for c in range(COLS) if self.board[0, c] == 0]
+
+    def legal_moves_mask(self):
+        """Return binary mask of legal columns."""
+        return (self.board[0] == 0).astype(np.float32)
+
+    def step(self, col):
+        """Play a move in the given column. Returns (state, reward, done)."""
+        if self.done:
+            raise ValueError("Game is already over.")
+        if col < 0 or col >= COLS or self.board[0, col] != 0:
+            raise ValueError(f"Illegal move: column {col}")
+
+        # Drop piece
+        row = self._get_drop_row(col)
+        self.board[row, col] = self.current_player
+        self.move_count += 1
+
+        # Check win
+        if self._check_win(row, col):
+            self.done = True
+            self.winner = self.current_player
+            reward = 1.0
+        elif self.move_count == ROWS * COLS:
+            self.done = True
+            self.winner = 0
+            reward = 0.0
+        else:
+            reward = 0.0
+
+        # Switch player
+        self.current_player *= -1
+        return self.get_state(), reward, self.done
+
+    def _get_drop_row(self, col):
+        for r in range(ROWS - 1, -1, -1):
+            if self.board[r, col] == 0:
+                return r
+        raise ValueError(f"Column {col} is full")
+
+    def _check_win(self, row, col):
+        player = self.board[row, col]
+        directions = [(0, 1), (1, 0), (1, 1), (1, -1)]
+        for dr, dc in directions:
+            count = 1
+            for sign in (1, -1):
+                r, c = row + sign * dr, col + sign * dc
+                while 0 <= r < ROWS and 0 <= c < COLS and self.board[r, c] == player:
+                    count += 1
+                    r += sign * dr
+                    c += sign * dc
+            if count >= WIN_LENGTH:
+                return True
+        return False
+
+    def clone(self):
+        g = ConnectFour()
+        g.board = self.board.copy()
+        g.current_player = self.current_player
+        g.done = self.done
+        g.winner = self.winner
+        g.move_count = self.move_count
+        return g