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Vinicius Ottoni
Vinicius Ottoni

Reputation: 4677

Select unique elements

I have the following Class:

public class Test
{
     public string ColumnA { get; set; }
     public int ColumnB { get; set; }
     public int ColumnC { get; set; }
}

An the following list:

List<Test> testList = new List<Test>()
{
    new Test() { ColumnA = "Element 1", ColumnB = 1, ColumnC = 3 },
    new Test() { ColumnA = "Element 2", ColumnB = 2, ColumnC = 2 },
    new Test() { ColumnA = "Element 3", ColumnB = 1, ColumnC = 3 },
    new Test() { ColumnA = "Element 4", ColumnB = 4, ColumnC = 4 },
    new Test() { ColumnA = "Element 5", ColumnB = 5, ColumnC = 5 },
    new Test() { ColumnA = "Element 6", ColumnB = 7, ColumnC = 0 },
    new Test() { ColumnA = "Element 7", ColumnB = 7, ColumnC = 0 }
};

So, I want to select only the unique elements (that the column B and C don't is the same comparing with other elements), that is: "Element 2", "Element 4" and "Element 5".

Obs: I don't want to bring distinct elements, the elements that are repeated I don't want to bring it, both of them.

How can I do that?

Upvotes: 0

Views: 124

Answers (4)

McGarnagle
McGarnagle

Reputation: 102763

Using Linq to select elements that don't have a duplicate:

Test[] noDupes = testList.Where(item => 
    !testList.Except(new[] { item }).Any(inner => inner.Equals(item))
).ToArray();

(This assumes you've implemented Equals on Test, of course.)

Upvotes: 0

fiinix
fiinix

Reputation: 142

One could write 

    List<Test> data = testList.FindAll(test => test.ColumnB == test.ColumnC);

The method FindAll is optimized due member of List<T>.FindAll

Upvotes: -1

MarcinJuraszek
MarcinJuraszek

Reputation: 125630

var results = source.GroupBy(x => new { x.ElementB, x.ElementC })
                    .Where(g => g.Count() == 1)
                    .Select(g => g.Single());

Just group using ElementB and ElementC properties and take elements from groups that have only one element within it (what means they are unique).

Upvotes: 3

Jonesopolis
Jonesopolis

Reputation: 25370

What about lambda 

    List<Test> answer = testList.Where(t => t.ColumnB == t.ColumnC).ToList();

Upvotes: 0

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