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Group Number in a LINQ Group by Query

Tags:

c#

linq

group-by

I've been using 101 LINQ Samples to get my feet wet using LINQ. It's been a good first resource, but I can't see an example there of what I currently need.

I just need to associate a sequential group number with each group. I have a working solution:

var groups =
   from c in list
   group c by c.Name into details
   select new { Name = details.Key, DetailRecords = details };


int groupNumber = 0;
foreach (var group in groups)
{
   // 
   // process each group and it's records ...
   // 

   groupNumber++;
}

But, I'm sure it's possible to use LINQ to also generate the groupNumber. How?

like image 861
Dave M Avatar asked Jul 19 '10 17:07

Dave M


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2 Answers

This depends on your exact needs, but you can use:

var groupArray = groups.ToArray();

Similarly, you can use ToList. These data structures are sequential, and each group has an index.


If you do need the index on the object you create, another option is to use Select:

list.GroupBy(c => c.Name)
    .Select((details, ind) =>
    new
    {
        Name = details.Key,
        DetailRecords = details,
        Index = ind
    });
like image 69
Kobi Avatar answered Sep 30 '22 09:09

Kobi


this should do the trick:

int groupNumber = 0;
var groups =
   from c in list
   group c by c.Name into details
   select new { Name = details.Key, DetailRecords = details, grpNum = groupNumber++};
like image 34
Luiscencio Avatar answered Sep 30 '22 09:09

Luiscencio