views:

156

answers:

2

I have an object, that has many properties but the only two to worry about are:

myobject.ID which is an int
myobject.Names which is a HashSet

Then I have a List of those objects that looks something similar to this:

List<myobject>

I use Linq to get a some of the data into a repeater, but I'm not sure how to get the list of Names and how often they show up.

Want to use Linq to avoid having to loop through the data.

As my tags should show, this is an ASP.NET solution using C#.

Some clarification:
Lets say I have just three items in my list: Item 1 has John, Fred, Jack in its names. Item 2 has John, Fred, Joe in its names. Item 3 has John in its names.

I am trying to return the following: John - 3 Fred - 2 Jack - 1 Joe - 1

Also, as a note I am familiar with having to write my own comparer for my object, I'm just missing the 'how to' for the overall solution in my thoughts.

+6  A: 

Here is how I understand the problem that you are trying to solve. You have a list of myobjects. Each myobject has a property called Names which is a HashSet of strings (i.e., HashSet<string>). You want to count the number of times each string that appears in some myobject.Names appears in all the myobject.Names. That is, you have

"Alice", "Bob", "Charlie"
"Alice", "Bob", "Donald"
"Alice", "Donald", "Ernie"

as three myobject.Names and you want to see

"Alice", 3
"Bob", 2
"Charlie", 1
"Donald", 2
"Ernie", 1

If so:

var query = list.SelectMany(x => x.Names)
                .GroupBy(s => s)
                .Select(g => new { Name = g.Key, Count = g.Count() });

foreach(var result in query) {
    Console.WriteLine("Name: {0}, Count: {1}", result.Name, result.Count);
}

I do not see what role myobject.ID plays here. Please qualify.

Jason
myobject.ID doesn't really play a role, I just wanted to make it clear that it wasn't a simple HashSet object.
Clarence Klopfstein
Okay. Then I believe that the above addresses your question. Let me know if anything needs clarification.
Jason
Your example has GroupBy(s), but s doesn't exist.
Clarence Klopfstein
Sorry, should be `GroupBy(s => s)`.
Jason
Never mind... typo in my code. Still working out your solution to see if it works.
Clarence Klopfstein
Thank you for the solution.
Clarence Klopfstein
+2  A: 
var query = yourList
            .SelectMany(x => x.Names)
            .GroupBy(x => x, (y, z) => new { Name = y, Count = z.Count() });

// and to test...
foreach (var item in query)
{
    Console.WriteLine("{0} - {1}", item.Name, item.Count);
}
LukeH