Is there a way to convert a python chess board into a list of integers?

Question

I am trying to create a neural network to play chess, but first, I need to convert the chess board to a list of integers. I am using the python-chess module for the chess board and game. I currently have a chess board class, but cannot find a method to convert it into a list.

I have tried to use the chess_board.epd() method, but that returns a formatting scheme that is hard to convert.

Here is the code that I need:

board = chess.Board()  # Define board object
board.convert_to_int()  # Method I need

Right now, with the .epd() method I get "rnbqkbnr/pppppppp/8/8/8/5P2/PPPPP1PP/RNBQKBNR b KQkq -"

As you can see, it is very difficult to parse and convert to a list of integers as there are /8/ 's and /5P2/ .

The expected output is something like this (goes row by row):

[4, 2, 3, 5, 6, 3, 2, 4, 1, 1, 1, 1, 1, 1, 1, 1, ... -1, -1, -1, -1,-1, -1,-1, -1, -4, -2, -3, -5, -6, -3, -2, -4]

For example, these can be what integers map to the peices:

pawn - 1
knight - 2
bishop - 3
rook - 4
queen - 5
king - 6

And white can be positive integers and black can be negative integers.

Answer 1

Here's another version, using the unicode() method:

def convert_to_int(board):
    indices = '♚♛♜♝♞♟⭘♙♘♗♖♕♔'
    unicode = board.unicode()
    return [
        [indices.index(c)-6 for c in row.split()]
        for row in unicode.split('\n')
    ]

Answer 2

I just read the documntation of the chess module and created a simple abstract Class as you want.

import chess

class MyChess(chess.Board):

    mapped = {
        'P': 1,     # White Pawn
        'p': -1,    # Black Pawn
        'N': 2,     # White Knight
        'n': -2,    # Black Knight
        'B': 3,     # White Bishop
        'b': -3,    # Black Bishop
        'R': 4,     # White Rook
        'r': -4,    # Black Rook
        'Q': 5,     # White Queen
        'q': -5,    # Black Queen
        'K': 6,     # White King
        'k': -6     # Black King
        }

    def convert_to_int(self):
        epd_string = self.epd()
        list_int = []
        for i in epd_string:
            if i == " ":
                return list_int
            elif i != "/":
                if i in self.mapped:
                    list_int.append(self.mapped[i])
                else:
                    for counter in range(0, int(i)):
                        list_int.append(0)

Note:

Uppercase letters are for white pieces and lowercase letters are for black pieces. And 0 are for empty spaces in the chess board.

Answer 3

I made a function to convert the chess.Board object into a matrix

def make_matrix(board): #type(board) == chess.Board()
    pgn = board.epd()
    foo = []  #Final board
    pieces = pgn.split(" ", 1)[0]
    rows = pieces.split("/")
    for row in rows:
        foo2 = []  #This is the row I make
        for thing in row:
            if thing.isdigit():
                for i in range(0, int(thing)):
                    foo2.append('.')
            else:
                foo2.append(thing)
        foo.append(foo2)
    return foo

This returns a matrix or nested lists:

Output:

[['r', 'n', 'b', 'q', 'k', 'b', 'n', 'r'], 
['p', 'p', 'p', 'p', 'p', 'p', 'p', 'p'], 
['.', '.', '.', '.', '.', '.', '.', '.'], 
['.', '.', '.', '.', '.', '.', '.', '.'], 
['.', '.', '.', '.', '.', '.', '.', '.'], 
['.', '.', '.', '.', '.', '.', '.', '.'], 
['P', 'P', 'P', 'P', 'P', 'P', 'P', 'P'], 
['R', 'N', 'B', 'Q', 'K', 'B', 'N', 'R']]

Answer 4

I have posted the question on Github , and I found I got a more elegant solution there. It was the following:

>>> import chess
>>> board = chess.Board()
>>> [board.piece_type_at(sq) for sq in chess.SQUARES]  # Get Type of piece
[4, 2, 3, 5, 6, 3, 2, 4, 1, 1, 1, 1, 1, 1, 1, 1, ...]

Note the above version does not include negatives, so here is the imporved version:

def convert_to_int(board):
        l = [None] * 64
        for sq in chess.scan_reversed(board.occupied_co[chess.WHITE]):  # Check if white
            l[sq] = board.piece_type_at(sq)
        for sq in chess.scan_reversed(board.occupied_co[chess.BLACK]):  # Check if black
            l[sq] = -board.piece_type_at(sq)
        return [0 if v is None else v for v in l]

piece_type_list(chess.Board())

"""
Outpus:
[4, 2, 3, 5, 6, 3, 2, 4, 1, 1, 1, 1, 1, 1, 1, 1, None, None, None, None, None, None, None, None, None, None, None, None, 
None, None, None, None, None, None, None, None, None, None, None, None, None, None, None, None, None, None, None, None,
 -1, -1, -1, -1, -1, -1, -1, -1, -4, -2, -3, -5, -6, -3, -2, -4]
"""