Change game quality calculations (#833)

* Change game quality calculations

* Fix newbie matching integration test

* Line break in comment

server/config.py

@@ -89,12 +89,12 @@ def __init__(self):
         # Difference of cumulated rating of the teams
         self.MAXIMUM_RATING_IMBALANCE = 500
         # stdev of the ratings of all participating players
-        self.MAXIMUM_RATING_DEVIATION = 750
+        self.MAXIMUM_RATING_DEVIATION = 500
         # Quality bonus for each failed matching attempt per full team
         self.TIME_BONUS = 0.02
-        self.MAXIMUM_TIME_BONUS = 0.4
-        self.NEWBIE_TIME_BONUS = 0.2
-        self.MAXIMUM_NEWBIE_TIME_BONUS = 1.6
+        self.MAXIMUM_TIME_BONUS = 0.2
+        self.NEWBIE_TIME_BONUS = 0.9
+        self.MAXIMUM_NEWBIE_TIME_BONUS = 2.7
 
         self.TWILIO_ACCOUNT_SID = ""
         self.TWILIO_TOKEN = ""

server/matchmaker/algorithm/team_matchmaker.py

@@ -1,6 +1,7 @@
 import logging
 import statistics
 from collections import defaultdict
+from math import sqrt
 from typing import Dict, Iterable, List, NamedTuple, Set, Tuple
 
 from sortedcontainers import SortedList
@@ -281,17 +282,18 @@ def assign_game_quality(self, match: Match, team_size: int) -> GameCandidate:
                 newbie_bonus += min(search_newbie_bonus, config.MAXIMUM_NEWBIE_TIME_BONUS * num_newbies / team_size)
 
         rating_disparity = abs(match[0].cumulative_rating - match[1].cumulative_rating)
-        fairness = 1 - (rating_disparity / config.MAXIMUM_RATING_IMBALANCE)
+        unfairness = rating_disparity / config.MAXIMUM_RATING_IMBALANCE
         deviation = statistics.pstdev(ratings)
-        uniformity = 1 - (deviation / config.MAXIMUM_RATING_DEVIATION)
+        rating_variety = deviation / config.MAXIMUM_RATING_DEVIATION
 
-        quality = fairness * uniformity
-        if fairness < 0 and uniformity < 0:
-            quality *= -1
-        quality += newbie_bonus + time_bonus
+        # Visually this creates a cone in the unfairness-rating_variety plane
+        # that slowly raises with the time bonuses.
+        quality = 1 - sqrt(unfairness ** 2 + rating_variety ** 2) + time_bonus
+        if not any(team.has_top_player() for team in match):
+            quality += newbie_bonus
         self._logger.debug(
-            "bonuses: %s rating disparity: %s -> fairness: %f deviation: %f -> uniformity: %f -> game quality: %f",
-            newbie_bonus + time_bonus, rating_disparity, fairness, deviation, uniformity, quality)
+            "bonuses: %s rating disparity: %s -> unfairness: %f deviation: %f -> variety: %f -> game quality: %f",
+            newbie_bonus + time_bonus, rating_disparity, unfairness, deviation, rating_variety, quality)
         return GameCandidate(match, quality)
 
     def pick_noncolliding_games(self, games: List[GameCandidate]) -> List[Match]:

tests/data/test-data.sql

@@ -132,7 +132,7 @@ insert into leaderboard_rating (login_id, mean, deviation, total_games, leaderbo
   (102, 1500, 500, 0, 1),
   (102, 1500, 500, 0, 2),
   (105, 1400, 150, 20, 3),
-  (106, 1500, 75, 20, 3)
+  (106, 900, 75, 20, 3)
 ;
 
 -- legacy table for global rating

tests/unit_tests/test_matchmaker_algorithm_team_matchmaker.py

@@ -80,10 +80,10 @@ def test_team_matchmaker_algorithm(player_factory):
 
     matches, unmatched = matchmaker.find(s, 4)
 
-    assert set(matches[0][0].get_original_searches()) == {c1, s[2], s[5]}
-    assert set(matches[0][1].get_original_searches()) == {c3, s[1], s[6]}
-    assert set(matches[1][0].get_original_searches()) == {c4, s[4]}
-    assert set(matches[1][1].get_original_searches()) == {c2, s[0], s[3]}
+    assert set(matches[1][0].get_original_searches()) == {c1, s[2], s[5]}
+    assert set(matches[1][1].get_original_searches()) == {c3, s[1], s[6]}
+    assert set(matches[0][0].get_original_searches()) == {c4, s[4]}
+    assert set(matches[0][1].get_original_searches()) == {c2, s[0], s[3]}
     assert set(unmatched) == {s[7]}
     for match in matches:
         assert matchmaker.assign_game_quality(match, 4).quality > config.MINIMUM_GAME_QUALITY
@@ -259,7 +259,10 @@ def test_game_quality_time_bonus(s):
     team_b.register_failed_matching_attempt()
     quality_after = matchmaker.assign_game_quality((team_a, team_b), 3).quality
 
-    num_newbies = team_a.num_newbies() + team_b.num_newbies()
+    if team_a.has_top_player() or team_b.has_top_player():
+        num_newbies = 0
+    else:
+        num_newbies = team_a.num_newbies() + team_b.num_newbies()
 
     assert (
         quality_before
@@ -283,7 +286,10 @@ def test_game_quality_max_time_bonus(s):
         team_b.register_failed_matching_attempt()
     quality_after = matchmaker.assign_game_quality((team_a, team_b), 3).quality
 
-    num_newbies = team_a.num_newbies() + team_b.num_newbies()
+    if team_a.has_top_player() or team_b.has_top_player():
+        num_newbies = 0
+    else:
+        num_newbies = team_a.num_newbies() + team_b.num_newbies()
 
     assert (
         quality_before