Generate Chess Board Diagram from an array of positions in Python?

Question

I have an array which corresponds to the positions of pieces on a chessboard, like so:

['em', 'bn', 'em', 'wr', 'em', 'wp', 'em', 'em']
['br', 'em', 'bp', 'em', 'em', 'bn', 'wn', 'em']
['em', 'em', 'bp', 'bp', 'bp', 'em', 'wp', 'bp']
['bp', 'bp', 'em', 'bp', 'wn', 'em', 'wp', 'em']
....

The 'b' and 'w' signify black and white.

n: knight
r: rook
p: pawn
b: bishop
k: king
q: queen

I want to know if there exists some utility which can take this array or something similar and generate a picture of a chessboard. There exist lots of board generators that work on FEN or PGN notation but I don't have access to that. I did do a lot of searching on Google but I couldn't find anything.

Thank you!

score 4 · Accepted Answer · answered Jun 25 '19 at 13:40

It is not difficult to convert your representation to a standard one. For example, you can convert to FEN with a function like this:

import io

def board_to_fen(board):
    # Use StringIO to build string more efficiently than concatenating
    with io.StringIO() as s:
        for row in board:
            empty = 0
            for cell in row:
                c = cell[0]
                if c in ('w', 'b'):
                    if empty > 0:
                        s.write(str(empty))
                        empty = 0
                    s.write(cell[1].upper() if c == 'w' else cell[1].lower())
                else:
                    empty += 1
            if empty > 0:
                s.write(str(empty))
            s.write('/')
        # Move one position back to overwrite last '/'
        s.seek(s.tell() - 1)
        # If you do not have the additional information choose what to put
        s.write(' w KQkq - 0 1')
        return s.getvalue()

Testing it on some board data:

board = [
    ['bk', 'em', 'em', 'em', 'em', 'em', 'em', 'em'],
    ['em', 'bn', 'em', 'wr', 'em', 'wp', 'em', 'em'],
    ['br', 'em', 'bp', 'em', 'em', 'bn', 'wn', 'em'],
    ['em', 'em', 'bp', 'bp', 'bp', 'em', 'wp', 'bp'],
    ['bp', 'bp', 'em', 'bp', 'wn', 'em', 'wp', 'em'],
    ['em', 'em', 'em', 'em', 'em', 'em', 'em', 'em'],
    ['em', 'em', 'em', 'wk', 'em', 'em', 'em', 'em'],
    ['em', 'em', 'em', 'em', 'em', 'em', 'em', 'em'],
]
print(board_to_fen(board))
# k7/1n1R1P2/r1p2nN1/2ppp1Pp/pp1pN1P1/8/3K4/8 w KQkq - 0 1

Visualizing the FEN string for example in Chess.com produces:

Thank you so much! This was exactly what I was looking for – chomprrr Jun 25 '19 at 14:20 — chomprrr, Jun 25 '19 at 14:20

score 1 · Answer 2 · answered Jun 25 '19 at 16:07

Alternative, a little more functional approach to converting the board into FEN:

#!/usr/bin/env python3
from more_itertools import run_length


def convert_cell(value):
    if value == 'em':
        return None
    else:
        color, piece = value
        return piece.upper() if color == 'w' else piece.lower()


def convert_rank(rank):
    return ''.join(
        value * count if value else str(count)
        for value, count in run_length.encode(map(convert_cell, rank))
    )


def fen_from_board(board):
    return '/'.join(map(convert_rank, board)) + ' w KQkq - 0 1'


def main():
    board = [
        ['bk', 'em', 'em', 'em', 'em', 'em', 'em', 'em'],
        ['em', 'bn', 'em', 'wr', 'em', 'wp', 'em', 'em'],
        ['br', 'em', 'bp', 'em', 'em', 'bn', 'wn', 'em'],
        ['em', 'em', 'bp', 'bp', 'bp', 'em', 'wp', 'bp'],
        ['bp', 'bp', 'em', 'bp', 'wn', 'em', 'wp', 'em'],
        ['em', 'em', 'em', 'em', 'em', 'em', 'em', 'em'],
        ['em', 'em', 'em', 'wk', 'em', 'em', 'em', 'em'],
        ['em', 'em', 'em', 'em', 'em', 'em', 'em', 'em'],
    ]
    print(fen_from_board(board))


if __name__ == '__main__':
    main()

Thank you for contributing! This also seems promising – chomprrr Jun 25 '19 at 17:19 — chomprrr, Jun 25 '19 at 17:19

Generate Chess Board Diagram from an array of positions in Python?

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