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PGN parsing and writing

Parsing

.. autofunction:: chess.pgn.read_game

Writing

If you want to export your game with all headers, comments and variations, you can do it like this:

>>> import chess
>>> import chess.pgn
>>>
>>> game = chess.pgn.Game()
>>> game.headers["Event"] = "Example"
>>> node = game.add_variation(chess.Move.from_uci("e2e4"))
>>> node = node.add_variation(chess.Move.from_uci("e7e5"))
>>> node.comment = "Comment"
>>>
>>> print(game)
[Event "Example"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "?"]
[Black "?"]
[Result "*"]
<BLANKLINE>
1. e4 e5 { Comment } *

Remember that games in files should be separated with extra blank lines.

>>> print(game, file=open("/dev/null", "w"), end="\n\n")

Use the :class:`~chess.pgn.StringExporter()` or :class:`~chess.pgn.FileExporter()` visitors if you need more control.

Game model

Games are represented as a tree of moves. Each :class:`~chess.pgn.GameNode` can have extra information, such as comments. The root node of a game (:class:`~chess.pgn.Game` extends the :class:`~chess.pgn.GameNode`) also holds general information, such as game headers.

.. autoclass:: chess.pgn.Game
    :members:

    .. py:attribute:: headers

        A mapping of headers. By default, the following 7 headers are provided:

        >>> import chess.pgn
        >>>
        >>> game = chess.pgn.Game()
        >>> game.headers
        Headers(Event='?', Site='?', Date='????.??.??', Round='?', White='?', Black='?', Result='*')

    .. py:attribute:: errors

        A list of errors (such as illegal or ambiguous moves) encountered while
        parsing the game.

.. autoclass:: chess.pgn.GameNode
    :members:

    .. py:attribute:: parent

        The parent node or ``None`` if this is the root node of the game.

    .. py:attribute:: move

        The move leading to this node or ``None`` if this is the root node of the
        game.

    .. py:attribute:: nags
        :annotation: = set()

        A set of NAGs as integers. NAGs always go behind a move, so the root
        node of the game will never have NAGs.

    .. py:attribute:: comment
        :annotation: = ''

        A comment that goes behind the move leading to this node. Comments
        that occur before any moves are assigned to the root node.

    .. py:attribute:: starting_comment
        :annotation: = ''

        A comment for the start of a variation. Only nodes that
        actually start a variation (:func:`~chess.pgn.GameNode.starts_variation()`
        checks this) can have a starting comment. The root node can not have
        a starting comment.

    .. py:attribute:: variations

        A list of child nodes.

Visitors

Visitors are an advanced concept for game tree traversal.

.. autoclass:: chess.pgn.BaseVisitor
    :members:

The following visitors are readily available.

.. autoclass:: chess.pgn.GameCreator
    :members: handle_error, result

.. autoclass:: chess.pgn.HeaderCreator

.. autoclass:: chess.pgn.BoardCreator

.. autoclass:: chess.pgn.SkipVisitor

.. autoclass:: chess.pgn.StringExporter

.. autoclass:: chess.pgn.FileExporter

NAGs

Numeric anotation glyphs describe moves and positions using standardized codes that are understood by many chess programs. During PGN parsing, annotations like !, ?, !!, etc., are also converted to NAGs.

.. autodata:: chess.pgn.NAG_GOOD_MOVE
.. autodata:: chess.pgn.NAG_MISTAKE
.. autodata:: chess.pgn.NAG_BRILLIANT_MOVE
.. autodata:: chess.pgn.NAG_BLUNDER
.. autodata:: chess.pgn.NAG_SPECULATIVE_MOVE
.. autodata:: chess.pgn.NAG_DUBIOUS_MOVE

Skimming

These functions allow for quickly skimming games without fully parsing them.

.. autofunction:: chess.pgn.read_headers

.. autofunction:: chess.pgn.skip_game