CODEWITHSUNDEEP
c#linqlinq-to-objects
TheNoodle
TheNoodle

Reputation: 77

Linq to Objects Sum to List

Im designing a method that accepts a List<Bar>, and returns <List>BarGroup, grouped by Bar.barName. My guess is I need to use Aggregate with List.Add, but I am fairly new to lambdas and Linq's syntax!

My code so far:

public class BarGroup
{
   public string barName;
   public List<Bar> barList;
}

public class Bar
{
   public string barName;
   public string fooDetails;

   public Bar(string b, string f)
   {
       this.barName = b;
       this.fooDetails = f;
   }
}

void Main()
{
    Bar bar1 = new Bar("BarGroup1","Bar1");
    Bar bar2 = new Bar("BarGroup1","Bar2");
    Bar bar3 = new Bar("BarGroup2", "Bar3");
    Bar bar4 = new Bar("BarGroup2", "Bar4");

    List<Bar> bars = new List<Bar> { bar1, bar2, bar3, bar4 };

    var barGrouped = from b in bars
                group b by b.barName into g
                select new BarGroup()
                {
                    barName = g.Key, 
                    barList = bars
                };

    Console.WriteLine(barGrouped);
}

When I try this in LinqPad, I get the following result:

IEnumerable<BarGroup> (2 items)
barName     barList 
BarGroup1   List<Bar> (4 items)
            barName    fooDetails 
            BarGroup1  Bar1 
            BarGroup1  Bar2 
            BarGroup2  Bar3 
            BarGroup2  Bar4 

BarGroup2   List<Bar> (4 items)
            barName    fooDetails 
            BarGroup1  Bar1 
            BarGroup1  Bar2 
            BarGroup2  Bar3 
            BarGroup2  Bar4

But what I'm looking for is below:

IEnumerable<BarGroup> (2 items)
barName     barList 
BarGroup1   List<Bar> (4 items)
            barName    fooDetails 
            BarGroup1  Bar1 
            BarGroup1  Bar2 

BarGroup2   List<Bar> (4 items)
            barName    fooDetails 
            BarGroup2  Bar3 
            BarGroup2  Bar4

I assumed Linq was the best choice for this type of splitting, but I am open to any other methods that accomplish the same task.

Upvotes: 0

Views: 403

Answers (1)

Stilgar
Stilgar

Reputation: 23551

Try

var barGrouped = from b in bars
            group b by b.barName into g
            select new BarGroup()
            {
                barName = g.Key, 
                barList = g.ToList()
            };

The group is IEnumerable<Bar> that satisfy the grouping criteria. bars is the original collection and this is why in your BarGroups you get all the items.

Upvotes: 1

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