184 lines
5.6 KiB
Python
184 lines
5.6 KiB
Python
import chess
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import chess.engine
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import sys
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# Eval constants for scoring chess boards
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# Evaluation metric inspired by Tomasz Michniewski: https://www.chessprogramming.org/Simplified_Evaluation_Function
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PIECE_VALUES = {
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chess.PAWN: 100,
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chess.KNIGHT: 320,
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chess.BISHOP: 330,
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chess.ROOK: 500,
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chess.QUEEN: 900,
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chess.KING: 20000
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}
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pawn_eval = [
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0, 0, 0, 0, 0, 0, 0, 0,
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5, 10, 10, -20, -20, 10, 10, 5,
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5, -5, -10, 0, 0, -10, -5, 5,
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0, 0, 0, 20, 20, 0, 0, 0,
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5, 5, 10, 25, 25, 10, 5, 5,
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10, 10, 20, 30, 30, 20, 10, 10,
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50, 50, 50, 50, 50, 50, 50, 50,
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0, 0, 0, 0, 0, 0, 0, 0
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]
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knight_eval = [
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-50, -40, -30, -30, -30, -30, -40, -50,
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-40, -20, 0, 0, 0, 0, -20, -40,
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-30, 0, 10, 15, 15, 10, 0, -30,
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-30, 5, 15, 20, 20, 15, 5, -30,
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-30, 0, 15, 20, 20, 15, 0, -30,
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-30, 5, 10, 15, 15, 10, 5, -30,
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-40, -20, 0, 5, 5, 0, -20, -40,
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-50, -40, -30, -30, -30, -30, -40, -50
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]
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bishop_eval = [
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-20, -10, -10, -10, -10, -10, -10, -20,
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-10, 5, 0, 0, 0, 0, 5, -10,
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-10, 10, 10, 10, 10, 10, 10, -10,
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-10, 0, 10, 10, 10, 10, 0, -10,
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-10, 5, 5, 10, 10, 5, 5, -10,
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-10, 0, 5, 10, 10, 5, 0, -10,
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-10, 0, 0, 0, 0, 0, 0, -10,
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-20, -10, -10, -10, -10, -10, -10, -20
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]
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rook_eval = [
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0, 0, 0, 5, 5, 0, 0, 0,
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-5, 0, 0, 0, 0, 0, 0, -5,
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-5, 0, 0, 0, 0, 0, 0, -5,
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-5, 0, 0, 0, 0, 0, 0, -5,
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-5, 0, 0, 0, 0, 0, 0, -5,
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-5, 0, 0, 0, 0, 0, 0, -5,
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5, 10, 10, 10, 10, 10, 10, 5,
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0, 0, 0, 0, 0, 0, 0, 0
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]
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queen_eval = [
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-20, -10, -10, -5, -5, -10, -10, -20,
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-10, 0, 0, 0, 0, 0, 0, -10,
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-10, 0, 5, 5, 5, 5, 0, -10,
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-5, 0, 5, 5, 5, 5, 0, -5,
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0, 0, 5, 5, 5, 5, 0, -5,
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-10, 5, 5, 5, 5, 5, 0, -10,
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-10, 0, 5, 0, 0, 0, 0, -10,
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-20, -10, -10, -5, -5, -10, -10, -20
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]
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king_eval = [
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20, 30, 10, 0, 0, 10, 30, 20,
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20, 20, 0, 0, 0, 0, 20, 20,
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-10, -20, -20, -20, -20, -20, -20, -10,
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20, -30, -30, -40, -40, -30, -30, -20,
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-30, -40, -40, -50, -50, -40, -40, -30,
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-30, -40, -40, -50, -50, -40, -40, -30,
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-30, -40, -40, -50, -50, -40, -40, -30,
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-30, -40, -40, -50, -50, -40, -40, -30
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]
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king_endgame_eval = [
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50, -30, -30, -30, -30, -30, -30, -50,
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-30, -30, 0, 0, 0, 0, -30, -30,
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-30, -10, 20, 30, 30, 20, -10, -30,
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-30, -10, 30, 40, 40, 30, -10, -30,
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-30, -10, 30, 40, 40, 30, -10, -30,
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-30, -10, 20, 30, 30, 20, -10, -30,
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-30, -20, -10, 0, 0, -10, -20, -30,
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-50, -40, -30, -20, -20, -30, -40, -50
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]
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PIECE_TABLES = {
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chess.WHITE: {
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chess.PAWN: pawn_eval,
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chess.KNIGHT: knight_eval,
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chess.BISHOP: bishop_eval,
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chess.ROOK: rook_eval,
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chess.QUEEN: queen_eval,
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chess.KING: king_eval,
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'end_game_king': king_endgame_eval
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},
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chess.BLACK: {
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chess.PAWN: list(reversed(pawn_eval)),
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chess.KNIGHT: list(reversed(knight_eval)),
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chess.BISHOP: list(reversed(bishop_eval)),
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chess.ROOK: list(reversed(rook_eval)),
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chess.QUEEN: list(reversed(queen_eval)),
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chess.KING: list(reversed(king_eval)),
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'end_game_king': list(reversed(king_endgame_eval))
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}
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}
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def check_endgame(board: chess.Board) -> bool:
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"""
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Endgame according to Tomasz Michniewski:
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1. Both sides have no queens or
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2. Every side which has a queen has additionally no other pieces or one minorpiece maximum.
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"""
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queens_white = 0
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minors_white = 0
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queens_black = 0
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minors_black = 0
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for s in chess.SQUARES:
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piece = board.piece_at(s)
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if piece is None:
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continue
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if piece.piece_type == chess.QUEEN:
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if piece.color == chess.WHITE:
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queens_white += 1
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else:
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queens_black += 1
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if piece.piece_type == chess.BISHOP or piece.piece_type == chess.KNIGHT:
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if piece.color == chess.WHITE:
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minors_white += 1
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else:
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minors_black += 1
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return (queens_black == 0 and queens_white == 0) or ((queens_black >= 1 >= minors_black) or (
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queens_white >= 1 >= minors_white))
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def score_manual(board: chess.Board) -> int:
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"""
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Calculate the score of the given board regarding the given color
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:param board: the chess board
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:return: score metric
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"""
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outcome = board.outcome()
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if outcome is not None:
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if outcome.termination == chess.Termination.CHECKMATE:
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return sys.maxsize if outcome.winner == chess.WHITE else -sys.maxsize
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else: # draw
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return 0
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score = 0
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for s in chess.SQUARES:
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piece = board.piece_at(s)
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if piece is None:
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continue
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if piece.color == chess.WHITE:
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if piece.piece_type == chess.KING and check_endgame(board):
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score += PIECE_VALUES[piece.piece_type] * PIECE_TABLES[chess.WHITE]['end_game_king'][s]
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else:
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score += PIECE_VALUES[piece.piece_type] * PIECE_TABLES[chess.WHITE][piece.piece_type][s]
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else:
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if piece.piece_type == chess.KING and check_endgame(board):
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score -= PIECE_VALUES[piece.piece_type] * PIECE_TABLES[chess.BLACK]['end_game_king'][s]
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else:
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score -= PIECE_VALUES[piece.piece_type] * PIECE_TABLES[chess.BLACK][piece.piece_type][s]
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return score
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def score_stockfish(board: chess.Board) -> chess.engine.PovScore:
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"""
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Calculate the score of the given board using stockfish
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:param board:
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:return:
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"""
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engine = chess.engine.SimpleEngine.popen_uci("./stockfish/stockfish-ubuntu-x86-64-avx2")
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info = engine.analyse(board, chess.engine.Limit(depth=0))
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engine.quit()
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return info["score"]
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