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Add SF 15.1 win rate model #943

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Merged
niklasf merged 1 commit into from
Dec 18, 2022
Merged

Add SF 15.1 win rate model #943

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20 changes: 17 additions & 3 deletions chess/engine.py
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Original file line number Diff line number Diff line change
Expand Up @@ -44,7 +44,7 @@

try:
from typing import Literal
_WdlModel = Literal["sf", "sf15", "sf14", "sf12", "lichess"]
_WdlModel = Literal["sf", "sf15.1", "sf15", "sf14", "sf12", "lichess"]
except ImportError:
# Before Python 3.8.
_WdlModel = str # type: ignore
Expand Down Expand Up @@ -564,7 +564,8 @@ def wdl(self, *, model: _WdlModel = "sf", ply: int = 30) -> Wdl:

:param model:
* ``sf``, the WDL model used by the latest Stockfish
(currently ``sf15``).
(currently ``sf15.1``).
* ``sf15.1``, the WDL model used by Stockfish 15.1.
* ``sf15``, the WDL model used by Stockfish 15.
* ``sf14``, the WDL model used by Stockfish 14.
* ``sf12``, the WDL model used by Stockfish 12.
Expand Down Expand Up @@ -628,6 +629,16 @@ def __ge__(self, other: object) -> bool:
return NotImplemented


def _sf15_1_wins(cp: int, *, ply: int) -> int:
# https://github.com/official-stockfish/Stockfish/blob/sf_15.1/src/uci.cpp#L200-L224
# https://github.com/official-stockfish/Stockfish/blob/sf_15.1/src/uci.h#L38
NormalizeToPawnValue = 361
m = min(240, max(ply, 0)) / 64
a = (((-0.58270499 * m + 2.68512549) * m + 15.24638015) * m) + 344.49745382
b = (((-2.65734562 * m + 15.96509799) * m + -20.69040836) * m) + 73.61029937
x = min(4000, max(cp * NormalizeToPawnValue / 100, -4000))
return int(0.5 + 1000 / (1 + math.exp((a - x) / b)))

def _sf15_wins(cp: int, *, ply: int) -> int:
# https://github.com/official-stockfish/Stockfish/blob/sf_15/src/uci.cpp#L200-L220
m = min(240, max(ply, 0)) / 64
Expand Down Expand Up @@ -678,9 +689,12 @@ def wdl(self, *, model: _WdlModel = "sf", ply: int = 30) -> Wdl:
elif model == "sf14":
wins = _sf14_wins(self.cp, ply=ply)
losses = _sf14_wins(-self.cp, ply=ply)
else:
elif model == "sf15":
wins = _sf15_wins(self.cp, ply=ply)
losses = _sf15_wins(-self.cp, ply=ply)
else:
wins = _sf15_1_wins(self.cp, ply=ply)
losses = _sf15_1_wins(-self.cp, ply=ply)
draws = 1000 - wins - losses
return Wdl(wins, draws, losses)

Expand Down
1 change: 1 addition & 0 deletions test.py
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Expand Up @@ -2969,6 +2969,7 @@ def test_wdl_model(self):
self.assertEqual(chess.engine.Cp(131).wdl(model="sf12", ply=25), chess.engine.Wdl(524, 467, 9))
self.assertEqual(chess.engine.Cp(146).wdl(model="sf14", ply=25), chess.engine.Wdl(601, 398, 1))
self.assertEqual(chess.engine.Cp(40).wdl(model="sf15", ply=25), chess.engine.Wdl(58, 937, 5))
self.assertEqual(chess.engine.Cp(100).wdl(model="sf15.1", ply=64), chess.engine.Wdl(497, 503, 0))

@catchAndSkip(FileNotFoundError, "need stockfish")
def test_sf_forced_mates(self):
Expand Down