LINQ Query with grouping and ranking

Question

I have a sql table called predictions with data as below

Week    Player     Points
201101  Mark       7
201101  Mark       7
201101  Pete       7
201101  Pet         


        

Answer 1

It was somewhat confusing to see that your query didn't seem to correspond to the data. So instead, this will be based on the data alone. The query should produce valid SQL so you won't have to use LINQ to Objects. You can adapt it to your tables with little modification.

var query = from pred in Predictions
            group pred.Points by pred.WeekNum into week
            join pred in Predictions
                on new { WeekNum = week.Key, Points = week.Max() }
                equals new { pred.WeekNum, pred.Points }
            group 1 by pred.Player into player
            let Wins = player.Count()
            orderby Wins descending, player.Key
            select new
            {
                Player = player.Key,
                Wins,
            };

Answer 2

Just pass a datatable to following function (Please note that the code is in c#) //dt should contain column points but not rank column

 public static DataTable GetRankedDatatable(DataTable dt)
            {
                var rankedDt = (from row in dt.AsEnumerable()
                                orderby row.Field<string>("points")
                                select row).CopyToDataTable();
                rankedDt.Columns.Add("rank");
                int rank = 0;
                for (int i = 0; i < rankedDt.Rows.Count - 1; i++)
                {
                    rankedDt.Rows[i]["rank"] = rank;
                    if (rankedDt.Rows[i]["points"].ToString() != rankedDt.Rows[i + 1]["points"].ToString())
                    {
                        rank++;
                    }
                }
                rankedDt.Rows[rankedDt.Rows.Count - 1]["rank"] = rank;
                return rankedDt;
            }

Answer 3

This code seems to be what you need:

    var result = this.DataList
            .GroupBy(data => data.Week)
            .Select(data=>
            {
                return data.GroupBy(item => item.Name)
                    .Select(item => new { Name = item.Key, SumPoints = item.Sum(v => v.Points) })
                    .OrderBy(item => item.SumPoints)
                    .FirstOrDefault();
            })
            .GroupBy(_=>_.Name)
            .ToDictionary(_=>_.Key, _=>_.Count());

Answer 4

mine is quite long

var weeklyTopScore = from eachMatch in FootballPredictions
                     group eachMatch by eachMatch.week
                     into weekly
                     select new {week = weekly.Key, topScore = weekly.Max(match => match.points)};

var playerWins = from eachResult in weeklyTopScore
                 join entry in FootballPredictions
                 on eachResult.week equals entry.week
                 where eachResult.topScore == entry.points
                 group entry by entry.player
                 into winner
                 select new { player = winner.Key, wins = winner.Count() };

var result = from entry in playerWins
             group entry by entry.wins
             into summary
             select new { player = summary.Select(data => data.player).Aggregate((cur, nex) => cur + ", " + nex), wins = summary.Key};

Answer 5

Try:

p.Points.Any()

Instead of:

p.Points != null