Merge pull request #954 from jacksonthall22/more-accurate-winning-chance

Update cp multiplier to match Lichess implementation
niklasf · Jan 26, 2023 · d13921c · d13921c
2 parents 57c9f87 + bc1c55a
commit d13921c
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/chess/engine.py b/chess/engine.py
@@ -664,7 +664,9 @@ def _sf12_wins(cp: int, *, ply: int) -> int:
     return int(0.5 + 1000 / (1 + math.exp((a - x) / b)))
 
 def _lichess_raw_wins(cp: int) -> int:
-    return round(1000 / (1 + math.exp(-0.004 * cp)))
+    # https://github.com/lichess-org/lila/pull/11148
+    # https://github.com/lichess-org/lila/blob/2242b0a08faa06e7be5508d338ede7bb09049777/modules/analyse/src/main/WinPercent.scala#L26-L30
+    return round(1000 / (1 + math.exp(-0.00368208 * cp)))
 
 
 class Cp(Score):