Question

This is what I have

ID Value
1  Val1
1  Val2
3  Val3   
3  Val4
4  Val5

I need

ID Value
1  Val1, Val2
3  Val3, Val4
5  Val4

I am stuck at this point:

      var groups = Result.GroupBy(res => res.ID);      
      foreach (var group in groups)
      {                       
        foreach (var entry in group)
        {

        }
       }

How to get the result into a new anonymous type?

Note, I also need a concrete type that can be serialized as well.

EDIT: The final solution was like

[Serializable]   
public class KeyValueCSV 
{
    public decimal Key { get;set;}
    public string CSVValues { get;set;}
}

List<KeyValueCSV> kvCSVList = new List<KeyValueCSV>();
KeyValueCSV kvCSV;

          var groups = Result.GroupBy(res => res.ID);      
          foreach (var group in groups)
          {  kvCSV = new KeyValueCSV();  
            foreach (var entry in group)
            {
               kvCSV.id = entry.id;
               kv.CSVValues = enrty.Value + ", ";
            }
           kvCSVList.Add(kvCSV);
           }

Answer 1

Group has everything you need

[Serializable]   
public class KeyValueCSV 
{
    public string Key { get;set;}
    public List<string> CSVValues { get;set;}
}

 var groups = 
       Result.GroupBy(res => res.ID)
       .Select(x => new KeyValueCSV() { 
            Key=x.key, 
            CSVValues= string.Join(",", x.ToList()) 
           }
       );

---

You could also do it:

var groups = (
from res in Result
group r by res.ID
into grouping

select
   new  KeyValueCSV()
   {
     Key =  grouping.Key,
     CSVValues=  string.Join(",", grouping.ToList())
   }
);

**Let me know if I messed something up 😉 I have been in the world of python recently so I might have managed to mix up some sytax…