Question

我尽力学习LINQ，但我仍然很难编写它。像这样，假设我有一个数据集或列表可能，集合对象的名称或字段是列名。

Id |日期|周一|周二|周三|周四   |周五|周六|周日|计数

1 | 01/05 | = 1 = | == 1 == | == 1 = | == 1 = |   1 = | = 0 = | = 0 == | == 5＆lt; - （1）

2 | 02/02 | = 1 = | == 1 == | == 1 = | == 1 = |   1 = | = 0 = | = 0 == | == 5 ** | - （2）

3 | 03/02 | = 1 = | == 1 == | == 1 = | == 1 = |   1 = | = 0 = | = 0 == | == 5 ** | - （2）

4 | 04/06 | = 1 = | == 1 == | == 1 = | == 1 = |   1 = | = 1 = | = 1 == | == 7＆lt; - （1）

5 | 05/04 | = 1 = | == 1 == | == 1 = | == 1 = |   1 = | = 1 = | = 1 == | == 7 ** | - （3）

6 | 06/01 | = 1 = | == 1 == | == 1 = | == 1 = |   1 = | = 1 = | = 1 == | == 7 ** | - （3）

7 | 07/06 | = 1 = | == 1 == | == 1 = | == 1 = |   0 = | = 0 = | = 0 == | == 4＆lt; ----（1）

8 | 08/03 | = 1 = | == 1 == | == 1 = | == 1 = |   0 = | = 0 = | = 0 == | == 4 ** | - （4）

9 | 09/07 | = 1 = | == 1 == | == 1 = | == 1 = |   0 = | = 0 = | = 0 == | == 4 ** | - （4）

10 | 10/05 | 1 = | == 1 == | == 1 = | == 1 = |   0 = | = 0 = | = 0 == | == 4 ** | - （4）

我想要的只是首先获得所有数字（1）然后得到（2）因为它们属于第一个（1）。接下来是（3）的组，因为它们属于第二个（1）。最后是（4）的组，因为它们属于最后一个（1）。

请帮忙。

- 问题改写。 1.我怎样才能获得第一组5分，然后是7分组，最后是4分组？

Answer 1

您似乎想要按计数订购。

当你说“得到第一组5个”时你的意思是什么 - 你想得到什么数据？

澄清之后

更新

假设

public class Row
{
    public int ID{get;set;}
    public string Date{get;set;}
    public int Count{get;set;}
}

Row r1 = new Row{ID=1, Date="01/01/01", Count=5};
Row r2 = new Row{ID=2, Date="01/02/01", Count=5};
Row r3 = new Row{ID=3, Date="01/03/01", Count=5};
Row r4 = new Row{ID=4, Date="01/04/01", Count=7};
Row r5 = new Row{ID=5, Date="01/05/01", Count=7};
Row r6 = new Row{ID=6, Date="01/06/01", Count=7};
Row r7 = new Row{ID=7, Date="01/07/01", Count=4};
Row r8 = new Row{ID=8, Date="01/08/01", Count=4};
Row r9 = new Row{ID=9, Date="01/09/01", Count=4};
Row r10 = new Row{ID=10, Date="01/01/01", Count=4};

List<Row> rows = new List<Row>{r1,r2,r3,r4,r5,r6,r7,r8,r9,r10};

然后

// We will assign results of our query to this variable
var result = 

// rows is a generic list of Row objects
rows                  

   // This splits the list into seperate categories organised by Count
   // After the GroupBy, we have an IEnumerable<IGrouping<Int32, Row>> - that is, a collection of collections of items sharing a common key (in this case Count)
   .GroupBy(r=>r.Count)  // r is of type Row

    // Now we are simply selecting the first item of each subgroup.
   .Select(g=>g.First()) // g is IGrouping<Int32,Row>, g.First() is of type Row
   ;

给出

   ID    Date        Count
    1    01/01/01    5
    4    01/04/01    7
    7    01/07/01    4

linq中的Noob，选择具有相同值的每条记录的第一条记录

1 个答案: