niklasf/python-chess

BinaryFen in python-chess

Torom opened this issue · 4 comments

Torom commented

You introduced the efficient BinaryFen in this blog post on Lichess.

My question is whether it would be possible to implement this in python-chess. I guess python-chess is used by quite a few people to store a lot of positions (at least I do). For this it would be very helpful to be able to use the space-saving and reversible BinaryFen.

Thank you for this awesome library.

vondele commented

indeed, would be real nice to have.

Torom commented

Here is my implementation in Python:

https://github.com/Torom/BinaryFen_python/blob/main/BinaryFen.py

It is definitely not perfect, pretty much a 1:1 conversion of Disservin's implementation.
So it also has no adaptations to variants.
And the size savings in Python also seem to be rather small:

>>> sys.getsizeof(bytearray(24))
81
>>> sys.getsizeof(chess.Board().epd())
93

Edit:
Okay apparently it was unnecessary to return bytearray. It gets better with bytes:

>>> sys.getsizeof(bytes(24))
57
niklasf commented

I'd imagine that this will be most useful when serializing to disk, so despite the relatively large memory usage as per sys.getsizeof(bytes(24)), it's really the 24 that makes it interesting.