feat: improve agreement algorithm (#184)

frontend/src/app/game/game/agreement.ts

@@ -1,49 +1,25 @@
 import {Vote} from "../model";
 
-
-interface VotedValue {
-  card: number;
-  totalVotes: number;
+export function calculateAgreement(votes: Array<Vote>): number | null {
+  const votedNumbers = votes.filter(vote => vote.voted && isVoteNumerical(vote));
+  return calculateAgreementInternal(votedNumbers.map(v => v.vote as number))
 }
 
-export function calculateAgreement(votes: Array<Vote>): number | null {
-  const totalVotes = votes.filter(vote => vote.voted && isVoteNumerical(vote)).length;
-  const votedValues = countVotedValues(votes);
-  if (votedValues.size === 0) {
+function calculateAgreementInternal(numbers: number[]): number | null {
+  if (numbers.length === 0) {
     return null;
-  } else if (votedValues.size === 1) {
-    return 100;
   }
-
-  const voteRatios = [...votedValues.entries()].map(entry => entry[1]/totalVotes);
-  const voteRationsStandardDeviation = standardDeviation(voteRatios, true);
-
-  return Math.round(Math.min(voteRationsStandardDeviation, 0.6) / (1 - 0.6) * 100);
+  const consensus: number = numbers.reduce((sum, num) => sum + num, 0) / numbers.length;
+  const deviationsFromConsensus: number[] = numbers.map(num => Math.abs(num - consensus));
+  const averageDeviation: number = deviationsFromConsensus.reduce((sum, deviation) => sum + deviation, 0) / deviationsFromConsensus.length;
+  const votedValueRange: number = Math.max(...numbers) - Math.min(...numbers);
+  const minMaxDeviationPercentage: number = 10;
+  const maxDeviationScalingFactor: number = 5;
+  const maxDeviationPercentage: number = Math.max(minMaxDeviationPercentage, 70 - (votedValueRange / maxDeviationScalingFactor));
+  const maxDeviation: number = (maxDeviationPercentage / 100) * consensus;
+  return Math.max(0, (1 - averageDeviation / maxDeviation) * 100);
 }
 
 export function isVoteNumerical(v: Vote): boolean {
   return v.vote != undefined && typeof v.vote == "number" && v.vote >= 0;
 }
-
-function countVotedValues(votes: Array<Vote>): Map<number, number> {
-  const countedVotedValues = new Map<number, number>();
-  votes.forEach(v => {
-    if (v.voted && isVoteNumerical(v)) {
-      const numericalVote = v.vote as number;
-      if (!countedVotedValues.has(numericalVote)) {
-        countedVotedValues.set(numericalVote, 0);
-      }
-      countedVotedValues.set(numericalVote, countedVotedValues.get(numericalVote)! + 1);
-    }
-  });
-  return countedVotedValues;
-}
-
-function standardDeviation(arr: Array<number>, usePopulation = false): number {
-  const mean = arr.reduce((acc, val) => acc + val, 0) / arr.length;
-  return Math.sqrt(
-    arr
-      .reduce((acc, val) => acc.concat((val - mean) ** 2), [] as Array<number>)
-      .reduce((acc, val) => acc + val, 0) / (arr.length - (usePopulation ? 0 : 1))
-  );
-}