replace BigDecimal with Int in FIDE perf rating calculation

lichess-org · Nov 11, 2024 · 7ed4bd8 · 7ed4bd8
1 parent 957507d
commit 7ed4bd8
Showing 1 changed file with 103 additions and 104 deletions.
diff --git a/core/src/main/scala/Elo.scala b/core/src/main/scala/Elo.scala
@@ -40,8 +40,7 @@ object Elo extends RelaxedOpaqueInt[Elo]:
   def computePerformanceRating(games: Seq[Game]): Option[Elo] =
     games.nonEmpty.option:
       val averageOpponentRating = games.map(_.opponentRating).sum / games.size
-      val percentageScore =
-        BigDecimal(games.map(_.points.value).sum / games.size).setScale(2, BigDecimal.RoundingMode.HALF_UP)
+      val percentageScore       = Math.round(games.map(_.points.value).sum * 100 / games.size)
       averageOpponentRating + performanceRatingTableFIDE.getOrElse(percentageScore, 0)
 
   final class Player(val rating: Elo, val kFactor: KFactor)
@@ -103,106 +102,106 @@ object Elo extends RelaxedOpaqueInt[Elo]:
   // https://handbook.fide.com/chapter/B022022 8.1.2
 
   // 1.4.9 FIDE table
-  val performanceRatingTableFIDE: Map[BigDecimal, Int] = Map(
-    BigDecimal("0.00") -> -800,
-    BigDecimal("0.01") -> -677,
-    BigDecimal("0.02") -> -589,
-    BigDecimal("0.03") -> -538,
-    BigDecimal("0.04") -> -501,
-    BigDecimal("0.05") -> -470,
-    BigDecimal("0.06") -> -444,
-    BigDecimal("0.07") -> -422,
-    BigDecimal("0.08") -> -401,
-    BigDecimal("0.09") -> -383,
-    BigDecimal("0.10") -> -366,
-    BigDecimal("0.11") -> -351,
-    BigDecimal("0.12") -> -336,
-    BigDecimal("0.13") -> -322,
-    BigDecimal("0.14") -> -309,
-    BigDecimal("0.15") -> -296,
-    BigDecimal("0.16") -> -284,
-    BigDecimal("0.17") -> -273,
-    BigDecimal("0.18") -> -262,
-    BigDecimal("0.19") -> -251,
-    BigDecimal("0.20") -> -240,
-    BigDecimal("0.21") -> -230,
-    BigDecimal("0.22") -> -220,
-    BigDecimal("0.23") -> -211,
-    BigDecimal("0.24") -> -202,
-    BigDecimal("0.25") -> -193,
-    BigDecimal("0.26") -> -184,
-    BigDecimal("0.27") -> -175,
-    BigDecimal("0.28") -> -166,
-    BigDecimal("0.29") -> -158,
-    BigDecimal("0.30") -> -149,
-    BigDecimal("0.31") -> -141,
-    BigDecimal("0.32") -> -133,
-    BigDecimal("0.33") -> -125,
-    BigDecimal("0.34") -> -117,
-    BigDecimal("0.35") -> -110,
-    BigDecimal("0.36") -> -102,
-    BigDecimal("0.37") -> -95,
-    BigDecimal("0.38") -> -87,
-    BigDecimal("0.39") -> -80,
-    BigDecimal("0.40") -> -72,
-    BigDecimal("0.41") -> -65,
-    BigDecimal("0.42") -> -57,
-    BigDecimal("0.43") -> -50,
-    BigDecimal("0.44") -> -43,
-    BigDecimal("0.45") -> -36,
-    BigDecimal("0.46") -> -29,
-    BigDecimal("0.47") -> -21,
-    BigDecimal("0.48") -> -14,
-    BigDecimal("0.49") -> -7,
-    BigDecimal("0.50") -> 0,
-    BigDecimal("0.51") -> 7,
-    BigDecimal("0.52") -> 14,
-    BigDecimal("0.53") -> 21,
-    BigDecimal("0.54") -> 29,
-    BigDecimal("0.55") -> 36,
-    BigDecimal("0.56") -> 43,
-    BigDecimal("0.57") -> 50,
-    BigDecimal("0.58") -> 57,
-    BigDecimal("0.59") -> 65,
-    BigDecimal("0.60") -> 72,
-    BigDecimal("0.61") -> 80,
-    BigDecimal("0.62") -> 87,
-    BigDecimal("0.63") -> 95,
-    BigDecimal("0.64") -> 102,
-    BigDecimal("0.65") -> 110,
-    BigDecimal("0.66") -> 117,
-    BigDecimal("0.67") -> 125,
-    BigDecimal("0.68") -> 133,
-    BigDecimal("0.69") -> 141,
-    BigDecimal("0.70") -> 149,
-    BigDecimal("0.71") -> 158,
-    BigDecimal("0.72") -> 166,
-    BigDecimal("0.73") -> 175,
-    BigDecimal("0.74") -> 184,
-    BigDecimal("0.75") -> 193,
-    BigDecimal("0.76") -> 202,
-    BigDecimal("0.77") -> 211,
-    BigDecimal("0.78") -> 220,
-    BigDecimal("0.79") -> 230,
-    BigDecimal("0.80") -> 240,
-    BigDecimal("0.81") -> 251,
-    BigDecimal("0.82") -> 262,
-    BigDecimal("0.83") -> 273,
-    BigDecimal("0.84") -> 284,
-    BigDecimal("0.85") -> 296,
-    BigDecimal("0.86") -> 309,
-    BigDecimal("0.87") -> 322,
-    BigDecimal("0.88") -> 336,
-    BigDecimal("0.89") -> 351,
-    BigDecimal("0.90") -> 366,
-    BigDecimal("0.91") -> 383,
-    BigDecimal("0.92") -> 401,
-    BigDecimal("0.93") -> 422,
-    BigDecimal("0.94") -> 444,
-    BigDecimal("0.95") -> 470,
-    BigDecimal("0.96") -> 501,
-    BigDecimal("0.97") -> 538,
-    BigDecimal("0.98") -> 589,
-    BigDecimal("0.99") -> 677,
-    BigDecimal("1.00") -> 800
+  val performanceRatingTableFIDE: Map[Int, Int] = Map(
+    0   -> -800,
+    1   -> -677,
+    2   -> -589,
+    3   -> -538,
+    4   -> -501,
+    5   -> -470,
+    6   -> -444,
+    7   -> -422,
+    8   -> -401,
+    9   -> -383,
+    10  -> -366,
+    11  -> -351,
+    12  -> -336,
+    13  -> -322,
+    14  -> -309,
+    15  -> -296,
+    16  -> -284,
+    17  -> -273,
+    18  -> -262,
+    19  -> -251,
+    20  -> -240,
+    21  -> -230,
+    22  -> -220,
+    23  -> -211,
+    24  -> -202,
+    25  -> -193,
+    26  -> -184,
+    27  -> -175,
+    28  -> -166,
+    29  -> -158,
+    30  -> -149,
+    31  -> -141,
+    32  -> -133,
+    33  -> -125,
+    34  -> -117,
+    35  -> -110,
+    36  -> -102,
+    37  -> -95,
+    38  -> -87,
+    39  -> -80,
+    40  -> -72,
+    41  -> -65,
+    42  -> -57,
+    43  -> -50,
+    44  -> -43,
+    45  -> -36,
+    46  -> -29,
+    47  -> -21,
+    48  -> -14,
+    49  -> -7,
+    50  -> 0,
+    51  -> 7,
+    52  -> 14,
+    53  -> 21,
+    54  -> 29,
+    55  -> 36,
+    56  -> 43,
+    57  -> 50,
+    58  -> 57,
+    59  -> 65,
+    60  -> 72,
+    61  -> 80,
+    62  -> 87,
+    63  -> 95,
+    64  -> 102,
+    65  -> 110,
+    66  -> 117,
+    67  -> 125,
+    68  -> 133,
+    69  -> 141,
+    70  -> 149,
+    71  -> 158,
+    72  -> 166,
+    73  -> 175,
+    74  -> 184,
+    75  -> 193,
+    76  -> 202,
+    77  -> 211,
+    78  -> 220,
+    79  -> 230,
+    80  -> 240,
+    81  -> 251,
+    82  -> 262,
+    83  -> 273,
+    84  -> 284,
+    85  -> 296,
+    86  -> 309,
+    87  -> 322,
+    88  -> 336,
+    89  -> 351,
+    90  -> 366,
+    91  -> 383,
+    92  -> 401,
+    93  -> 422,
+    94  -> 444,
+    95  -> 470,
+    96  -> 501,
+    97  -> 538,
+    98  -> 589,
+    99  -> 677,
+    100 -> 800
   )