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encoders/sevenplane.py

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+# tag::sevenplane_init[]
+import numpy as np
+
+from tugo.encoders.base import Encoder
+from tugo.goboard import Move, Point
+
+
+class SevenPlaneEncoder(Encoder):
+    def __init__(self, board_size):
+        self.board_width, self.board_height = board_size
+        self.num_planes = 7
+
+    def name(self):
+        return 'sevenplane'
+# end::sevenplane_init[]
+
+# tag::sevenplane_encode[]
+    def encode(self, game_state):
+        board_tensor = np.zeros(self.shape())
+        base_plane = {game_state.next_player: 0,
+                      game_state.next_player.other: 3}
+        for row in range(self.board_height):
+            for col in range(self.board_width):
+                p = Point(row=row + 1, col=col + 1)
+                go_string = game_state.board.get_go_string(p)
+                if go_string is None:
+                    if game_state.does_move_violate_ko(game_state.next_player,
+                                                       Move.play(p)):
+                        board_tensor[6][row][col] = 1  # <1>
+                else:
+                    liberty_plane = min(3, go_string.num_liberties) - 1
+                    liberty_plane += base_plane[go_string.color]
+                    board_tensor[liberty_plane][row][col] = 1  # <2>
+        return board_tensor
+# <1> Encoding moves prohibited by the ko rule
+# <2> Encoding black and white stones with 1, 2 or more liberties.
+# end::sevenplane_encode[]
+
+# tag::sevenplane_rest[]
+    def encode_point(self, point):
+        return self.board_width * (point.row - 1) + (point.col - 1)
+
+    def decode_point_index(self, index):
+        row = index // self.board_width
+        col = index % self.board_width
+        return Point(row=row + 1, col=col + 1)
+
+    def num_points(self):
+        return self.board_width * self.board_height
+
+    def shape(self):
+        return self.num_planes, self.board_height, self.board_width
+
+
+def create(board_size):
+    return SevenPlaneEncoder(board_size)
+# end::sevenplane_rest[]