Simple evaluation function

evaluation_function.py

def board_value(board: chess.Board) -> float:
	"""
	This functions receives a board and assigns a value to it, it acts as
	an evaluation function of the current state for this game. It returns


	Arguments:
		- board: current board state.

	Returns:
		- total_value(int): integer representing
		current value for this board.
	"""
	total_value = 0

	black_pieces, white_pieces = count_pieces(board)

	for row in range(8):
		for col in range(8):

			square_index = row*8+col
			square = chess.SQUARES[square_index]
			piece = board.piece_at(square)

			if piece:

				piece_color = piece.color

				#  adding to totalValue the value coming from black pieces.
				#  When the black is evaluating it will try to find the highest possible totalValue
				#  in this case meaning that it has more black pieces in the table and less white pieces
				if piece.symbol().lower() in PIECE_VALUES:
					if piece_color == chess.BLACK:
						total_value += PIECE_VALUES[piece.symbol().lower()]
					else:
						total_value -= PIECE_VALUES[piece.symbol().lower()]

				if piece.symbol().lower() == 'p':
					pawn_in_col = 0

					# count pawns in column
					for j in range(8):
						square_index_helper = j*8+col
						square_helper = chess.SQUARES[square_index_helper]
						piece_helper = board.piece_at(square_helper)
						if piece_helper and piece_helper.symbol().lower() == 'p' and piece_helper.color == piece_color:
							pawn_in_col += 1

					if pawn_in_col >= 2:
						if piece_color == chess.BLACK:
							total_value -= 0.5*pawn_in_col
						else:
							total_value += 0.5*pawn_in_col

				# if we are in the beginning of the game, we want to have a few different heuristics
				if white_pieces + black_pieces >= 27:
					# removing points for moving queen too early in the game
					if piece.symbol().lower() == 'q' and (row, col) not in QUEEN_START:
						if piece_color == chess.BLACK:
							total_value -= 6
						else:
							total_value += 6

					# points for moving knight early in the game
					if piece.symbol().lower() == 'n' and (row not in KNIGHT_ROW and (col != LEFT_KNIGHT_COL or col != RIGHT_KNIGHT_COL)):
						if piece_color == chess.BLACK:
							total_value += 3
						else:
							total_value -= 3

					# points for moving bishop early in the game
					# False
					if piece.symbol().lower() == 'b' and (row not in BISHOP_ROW and (col != LEFT_BISHOP_ROW or col != RIGHT_BISHOP_ROW)):
						if piece_color == chess.BLACK:
							total_value += 3
						else:
							total_value -= 3

					# points for dominating the middle squares
					# 4 squares in the center of the board
					if row in CENTER_ROWS and col in CENTER_ROWS:
						if piece_color == chess.BLACK:
							total_value += 0.07
						else:
							total_value -= 0.07

					# points for dominating the middle rows
					elif row in CENTER_ROWS and col in CENTER_COLUMNS:
						if piece_color == chess.BLACK:
							total_value += 0.06
						else:
							total_value -= 0.06

				# end game heuristics
				if white_pieces <= 6:
					if piece.symbol().lower() == 'k':
						if (row, col) in CORNERS:
							if piece_color == chess.WHITE:
								total_value += 9
							else:
								total_value -= 9

				elif black_pieces <= 6:
					if piece.symbol().lower() == 'k':
						if (row, col) in CORNERS:
							if piece_color == chess.BLACK:
								total_value -= 9
							else:
								total_value += 9

	return round(total_value, 2)