Noob in linq, selecting the first record of each record with the same value

Question

Hi guys,

im trying my best to learn LINQ but im still having a hard time coding it. Like this one, suppose I have a dataset or a List maybe and the names or fields of the of the collection object are the column names.

Id | Date |Mon |Tues |Wed |Thu |Fri |Sat |Sun |Count

1 | 01/05 |=1=|==1==|==1=|==1=| 1=|=0=|=0==|==5 <-- (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 <-- (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 <---- (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)

All i want is first to get all the number (1)'s then the (2)'s because they belong to the first (1). Next the group of (3)'s because they belong to the second (1). Last the group of (4)'s because they belong to the last (1).

please help.

-- question rephrased. 1. how can i get the first group of 5's then the group of 7's and last the group of 4's?

Answer 1

It appears you want to want to order by count.

When you say "get the first group of 5's" what do you mean - what data do you want to get?

UPDATE after clarification

Assuming

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};

Then

// 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
   ;

Gives

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