Question

希望得到一些帮助。

我正在从数据库中检索以下列表。

Name  AssessNumber Score
John     1            90
John     2            88
John     3            67
Steve    1            98
Steve    2            90

我想要的是按平均分数分组并显示最高分数（int）

Name   AssessNumber   Score
John   3              81.6
Steve  2              94

数据将存储在List<lbResults>lb = new List<lbResults>()

中

我怎样才能做到这一点？

亲切的问候

Answer 1

试试这个：

var results = data.GroupBy(x => x.Name).Select(x => new
{
    Name = x.Key,
    AssessNumber = x.Max(z => z.AssessNumber),
    Score = x.Average(z => z.Score)
})

您还可以返回原始数据结构（您命名为lbResults）：

var results = data.GroupBy(x => x.Name).Select(x => new lbResults
{
    Name = x.Key,
    AssessNumber = x.Max(z => z.AssessNumber),
    Score = x.Average(z => z.Score)
})

请参阅Fiddle

Answer 2

试试这个： -

List<lblResults> result = data.GroupBy(x => x.Name)
                              .Select(x => new lbResults 
                                          { 
                                             Name = x.Key, 
                                             AssessNumber = x.Max(z => z.AssesName), 
                                             Score = x.Average(s => s.Score) 
                                          }
                                       ).ToList();

Answer 3

我想要按平均分数分组

从输出中看，您希望按Name进行分组，并获得最高AssessNumber和平均Score。您的查询应该是：

var query = lb.GroupBy(r => r.Name)
              .Select(grp => new 
                  {
                     Name = grp.Key, 
                     AccessNumber = grp.Max(i=> i.AccessNumber), 
                     AverageScore = grp.Avg(i => i.Score),
                  });

Answer 4

假设：

public class lbResults
{
    public string Name { get; set; }
    public int Assess { get; set; }
    public int Score { get; set; }
}

你想要：

 List<lbResults> lb = new List<lbResults>
 {
      new lbResults{ Name="John", Assess = 1, Score=90},
      new lbResults{ Name="John", Assess = 2, Score=88},
      new lbResults{ Name="John", Assess = 3, Score=67},
      new lbResults{ Name="Steve", Assess = 1, Score=98},
      new lbResults{ Name="Steve", Assess = 2, Score=90},
 };

var results = lb.GroupBy(l => l.Name)
                .Select(g => new 
                        { 
                          Name = g.Key, 
                          Assess = g.Max(gr => gr.Assess), 
                          Score = g.Average(gr => gr.Score) 
                        });

Answer 5

让我们有球员：

var players = new List<Player> {
    new Player { Name = "John",  AssessNumber = 1, Score = 90 },
    new Player { Name = "John",  AssessNumber = 2, Score = 88 },
    new Player { Name = "John",  AssessNumber = 3, Score = 67 },
    new Player { Name = "Steve", AssessNumber = 1, Score = 98 },
    new Player { Name = "Steve", AssessNumber = 2, Score = 90 },
};

此代码显示使用 linq查询表达式语法：

进行分组

var playerInfos =
    from player in players
    group player by player.Name into playerGroup
    select new
    {
        PlayerName = playerGroup.Key,
        MaxAssessNumber = playerGroup.Max(x => x.AssessNumber),
        AverageScore = playerGroup.Average(x => x.Score),
    };

结果playerInfos是匿名对象的集合：

{ PlayerName = "John",  MaxAssessNumber = 3, AverageScore = 81.66666... }
{ PlayerName = "Steve", MaxAssessNumber = 2, AverageScore = 94.0 }

查看有关LINQ Average聚合方法的更多信息。

使用linq检索平均分数

5 个答案: