Exemple #1
0
        /// <summary>
        /// Gets the top two rated options.
        /// </summary>
        /// <param name="rankedVotes">The group votes.</param>
        /// <param name="option1">The top rated option. Null if there aren't any options available.</param>
        /// <param name="option2">The second rated option.  Null if there is only one option available.</param>
        private static void GetTopTwoRatedOptions(IEnumerable<RankGroupedVoters> rankedVotes,
            out string option1, out string option2, ref string debug)
        {
            var scoredVotes = from vote in rankedVotes
                              select new { Vote = vote.VoteContent, Rank = RankScoring.LowerWilsonScore(vote.Ranks) };

            var orderedVotes = scoredVotes.OrderByDescending(a => a.Rank);

            var topTwo = orderedVotes.Take(2);

            var v1 = topTwo.FirstOrDefault();
            var v2 = topTwo.Skip(1).FirstOrDefault();

            option1 = v1?.Vote;
            option2 = v2?.Vote;

            StringBuilder sb = new StringBuilder();

            // Output: [Option1, Option2] [Score1, Score2] [PrefCount1, PrefCount2]
            sb.Append("RIR: [");
            if (v1 != null)
                sb.Append(v1.Vote);
            sb.Append(", ");
            if (v2 != null)
                sb.Append(v2.Vote);
            sb.Append("] [");
            if (v1 != null)
                sb.Append($"{v1.Rank:f5}");
            sb.Append(", ");
            if (v2 != null)
                sb.Append($"{v2.Rank:f5}");
            sb.Append("] ");

            debug = sb.ToString();
        }
Exemple #2
0
        /// <summary>
        /// Gets the least preferred choice.
        /// This is normally determined by selecting the option with the lowest Borda count.
        /// This is inverted because we don't want to convert ranks to Borda values (it gains us nothing).
        /// It then needs to be averaged across the number of instances of each vote, to
        /// account for unranked options.  This allows apples-to-apples comparisons against options
        /// that are ranked in all votes.
        /// We then need to scale it relative to the number of instances of that option appearing, to deal
        /// with truncated rankings (where there are more options than rankings allowed).
        /// An option ranked infrequently can be scaled up relative to its rate of occurance for
        /// a high likelihood of elimination.
        /// </summary>
        /// <param name="localRankings">The vote rankings.</param>
        /// <returns>Returns the vote string for the least preferred vote.</returns>
        private static string GetLeastPreferredChoice(List <VoterRankings> localRankings)
        {
            var groupVotes = GroupRankVotes.GroupByVoteAndRank(localRankings);

            var rankedVotes = from vote in groupVotes
                              select new { Vote = vote.VoteContent, Rank = RankScoring.LowerWilsonScore(vote.Ranks) };

            var worstVote = rankedVotes.MinObject(a => a.Rank);

            Debug.Write($"({worstVote.Rank:f5}) {worstVote.Vote}");

            return(worstVote.Vote);
        }
Exemple #3
0
        /// <summary>
        /// Implementation to generate the ranking list for the provided set
        /// of votes for a specific task.
        /// </summary>
        /// <param name="task">The task that the votes are grouped under.</param>
        /// <returns>Returns a ranking list of winning votes.</returns>
        protected override RankResults RankTask(GroupedVotesByTask task)
        {
            // Can calculating the score easily by having all the rankings for
            // each vote grouped together.
            var groupVotes = GroupRankVotes.GroupByVoteAndRank(task);

            var rankedVotes = from vote in groupVotes
                              select new { Vote = vote.VoteContent, Rank = RankScoring.LowerWilsonScore(vote.Ranks) };

            var orderedVotes = rankedVotes.OrderByDescending(a => a.Rank);

            RankResults results = new RankResults();

            results.AddRange(orderedVotes.Select(a =>
                                                 new RankResult(a.Vote, $"Wilson: [{a.Rank:f5}]")));

            return(results);
        }