列表中的项目组基于使用LINQ两个属性 [英] Group items in a list based on two properties using LINQ

问题描述

我有如下一个列类：

public class Column
{
    public int LocId { get; set; }
    public int SecId { get; set; }
    public double StartElevation { get; set; }
    public double EndElevation { get; set; }
}

和列对象：

List<Column> Columns = new List<Column>();

例如：

Columns:
{
    Column1: { LocId = 1 , SecId = 1, StartElevation = 0, EndElevation = 160 }
    Column2: { LocId = 1 , SecId = 1, StartElevation = 160, EndElevation = 320 }
    Column3: { LocId = 1 , SecId = 2, StartElevation = 320, EndElevation = 640 }
    Column4: { LocId = 2 , SecId = 1, StartElevation = 0, EndElevation = 160 }
    Column5: { LocId = 2 , SecId = 2, StartElevation = 160, EndElevation = 320 }
}

我想用的LINQ 。

通过列列表，并转到：

• 的（A）选择具有相同 LOCID 。的

的（b），然后从列表中选择具有相同项目的另一个列表 SecId 。

这会给我希望清单，我将它执行其他的事情。

This will give me a list hopefully which I will perform other things on it.

因此应用上的数据，上述算法上面会是这样。

So applying the above algorithm on the data above will be like this.

                                       Columns List
                ---------------------------------------------------------
               | Column1     Column2     Column3     Column4     Column5 |
                ---------------------------------------------------------
                                            |
                                            |
                                           (A)
                                            |
                                            |
                        --------------------------------------------
                        |                                          |
                GroupBasedOnLocId                         GroupBasedOnLocId
                        |                                          |
                  -----------                                 -----------
                  | Column1 |                                 | Column4 |
                  | Column2 |                                 | Column5 |
                  | Column3 |                                 -----------
                  -----------                                      |
                       |                                           |
                      (B)                                         (B)
                       |                                           |
          -------------------------                   -------------------------
          |                       |                   |                       |
          |                       |                   |                       |
 GroupBasedOnSecId        GroupBasedOnSecId  GroupBasedOnSecId        GroupBasedOnSecId
          |                       |                   |                       |
          |                       |                   |                       |
       Column1                 Column3             Column4                 Column5
       Column2

我怎样才能做到这一点使用LINQ？

How can I accomplish this using Linq?

PS是的，我已经把大量的时间到创建上面的图来传达这个问题越好。

P.S. Yes, I've put lots of time into creating the above diagram to convey the question better.

推荐答案

使用<$ C $ 。C> .GroupBy 复合键

示例代码：

List<Column> Columns = new List<Column>
{
   new Column { LocId = 1 , SecId = 1, StartElevation = 0, EndElevation = 160 },
   new Column { LocId = 1 , SecId = 1, StartElevation = 160, EndElevation = 320 },
   new Column { LocId = 1 , SecId = 2, StartElevation = 320, EndElevation = 640 },
   new Column { LocId = 2 , SecId = 1, StartElevation = 0, EndElevation = 160 },
   new Column { LocId = 2 , SecId = 2, StartElevation = 160, EndElevation = 320 }
};

foreach (var group in Columns.GroupBy(c => new { c.LocId, c.SecId }))
{
    Console.WriteLine("group: LocId = {0}, SecId = {1}", group.Key.LocId, group.Key.SecId);
    foreach(Column column in group)
        Console.WriteLine("  item: StartElevation = {0}, EndElevation = {1}", column.StartElevation, column.EndElevation);
}

您可以将集团任何你想要的方式：

You can transform the group any way you want:

foreach (var res in Columns.GroupBy(c => new { c.LocId, c.SecId })
                           .Select(g => new
                           {
                               g.Key.LocId,
                               g.Key.SecId,
                               MinStartElevation = g.Min(c => c.StartElevation),
                               MaxEndElevation = g.Max(c => c.EndElevation)
                           }))
{
    Console.WriteLine("LocId = {0}, SecId = {1}, MinStartElevation = {2}, MaxEndElevation = {3}",
        res.LocId, res.SecId, res.MinStartElevation, res.MinStartElevation);
}

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