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use FIDE table for rating performance calculation #595

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Merged
merged 3 commits into from
Nov 11, 2024
Merged

use FIDE table for rating performance calculation #595

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beb17b5
implement FIDE table for rating performance calculation
aarew12 Nov 11, 2024
957507d
fix formatting
aarew12 Nov 11, 2024
7ed4bd8
replace BigDecimal with Int in FIDE perf rating calculation
ornicar Nov 11, 2024
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116 changes: 108 additions & 8 deletions core/src/main/scala/Elo.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -38,15 +38,10 @@ object Elo extends RelaxedOpaqueInt[Elo]:
if ratingDiff <= 0 then expectedScore else 1.0f - expectedScore

def computePerformanceRating(games: Seq[Game]): Option[Elo] =
val winBonus = 400
games.nonEmpty.option:
val ratings = games.map(_.opponentRating).sum
val points = games.foldMap:
_.points.match
case Outcome.Points.Zero => -1
case Outcome.Points.Half => 0
case Outcome.Points.One => 1
(ratings + points * winBonus) / games.size
val averageOpponentRating = games.map(_.opponentRating).sum / games.size
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)

Expand Down Expand Up @@ -105,3 +100,108 @@ object Elo extends RelaxedOpaqueInt[Elo]:
// the hardcoded List above is not really necessary,
// but it mirrors the reference table on
// https://handbook.fide.com/chapter/B022022 8.1.2

// 1.4.9 FIDE table
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
)
10 changes: 6 additions & 4 deletions test-kit/src/test/scala/EloTest.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -56,10 +56,12 @@ class EloTest extends ChessTest:
def loss(r: Int) = Elo.Game(Zero, Elo(r))
def draw(r: Int) = Elo.Game(Half, Elo(r))
assertEquals(Elo.computePerformanceRating(Nil), None)
perfRating(List(win(1500)), 1900)
perfRating(List(win(1500), win(1500)), 1900)
perfRating(List(loss(1500)), 1100)
perfRating(List(win(1500)), 2300)
perfRating(List(win(1500), win(1500)), 2300)
perfRating(List(loss(1500)), 700)
perfRating(List(draw(1500)), 1500)
perfRating(List(draw(1500), draw(1500)), 1500)
perfRating(List(win(1500), loss(1500)), 1500)
perfRating(List(win(1500), draw(1500)), 1700)
perfRating(List(win(1500), loss(1700)), 1600)
perfRating(List(win(1500), draw(1500)), 1693)
perfRating(List(win(1500), draw(1500), draw(1500)), 1625)