Question

For example , I have a class like below:

public class SampleItem
{
    public string QCD { get; set; }
    public string CCD { get; set; }
    public string ITYPE { get; set; }
}

Then, I have a list:

var lstTest = new List<SampleItem>() { 

    new SampleItem(){ QCD = "Q1" ,  CCD = "C1" , ITYPE = "A"} ,
    new SampleItem(){ QCD = "Q1" ,  CCD = "C2" , ITYPE = "A"} ,
    new SampleItem(){ QCD = "Q1" ,  CCD = "C3" , ITYPE = "A"} ,

    new SampleItem(){ QCD = "Q1" ,  CCD = "C1" , ITYPE = "B"} ,
    new SampleItem(){ QCD = "Q1" ,  CCD = "C2" , ITYPE = "B"} ,
};

I want to get 2 Groups like

Group 1 :

new SampleItem(){ QCD = "Q1" ,  CCD = "C1" , ITYPE = "A"} ,
new SampleItem(){ QCD = "Q1" ,  CCD = "C2" , ITYPE = "A"} ,
new SampleItem(){ QCD = "Q1" ,  CCD = "C3" , ITYPE = "A"} ,

Group 2 :

new SampleItem(){ QCD = "Q1" ,  CCD = "C1" , ITYPE = "B"} ,
new SampleItem(){ QCD = "Q1" ,  CCD = "C2" , ITYPE = "B"} ,

So, I just need

lstTest.GroupBy (p=>new {p.QCD ,p.ITYPE});

But now, if My List’s order is like the one below

var lstTest = new List<SampleItem>() { 

    new SampleItem(){ QCD = "Q1" ,  CCD = "C1" , ITYPE = "B"} ,
    new SampleItem(){ QCD = "Q1" ,  CCD = "C2" , ITYPE = "B"} ,

    new SampleItem(){ QCD = "Q1" ,  CCD = "C1" , ITYPE = "A"} ,
    new SampleItem(){ QCD = "Q1" ,  CCD = "C2" , ITYPE = "A"} ,
    new SampleItem(){ QCD = "Q1" ,  CCD = "C3" , ITYPE = "A"} ,

    new SampleItem(){ QCD = "Q1" ,  CCD = "C1" , ITYPE = "B"} ,
    new SampleItem(){ QCD = "Q1" ,  CCD = "C2" , ITYPE = "B"} ,
};

How can I get 3 Groups like

Group 1 :

new SampleItem(){ QCD = "Q1" ,  CCD = "C1" , ITYPE = "B"} ,
new SampleItem(){ QCD = "Q1" ,  CCD = "C2" , ITYPE = "B"} ,

Group 2 :

new SampleItem(){ QCD = "Q1" ,  CCD = "C1" , ITYPE = "A"} ,
new SampleItem(){ QCD = "Q1" ,  CCD = "C2" , ITYPE = "A"} ,
new SampleItem(){ QCD = "Q1" ,  CCD = "C3" , ITYPE = "A"} ,

Group 3 :

new SampleItem(){ QCD = "Q1" ,  CCD = "C1" , ITYPE = "B"} ,
new SampleItem(){ QCD = "Q1" ,  CCD = "C2" , ITYPE = "B"} ,

By LINQ?

Thank you kindly for any advice.

Answer 1

Using a GroupAdjacent operator, such as the one listed on Eric White’s blog, you can do:

var groupedItems = lstTest.GroupAdjacent(p => new { p.QCD, p.ITYPE });