How to find duplicate items based on multiple values using LINQ?

Question

Suppose I have the following class:

public class Test{
    public string Length { get; set; }
    public string Width { get; set; }
    public string Height { get; set; }
    public int Count { get; set; }
    public string Label { get; set; }
}

And I would like to find items that have the same value for length and label and counting how many there are for each. So far my code looks like:

var dups = testlist.GroupBy(i => new { i.Length, i.Label })
                   .Where(g => g.Count() >= 1)
                   .Select(g => new { Length = g.Key.Length, Label = g.Key.Label, 
                                      Count = g.Count() });

But the problem is, the objects in var no longer have the width or height property (they don't exist in g.Key). Is there anyway to find duplicates based on two properties while saving other properties in the result?

Since each group may have multiple items in it with different widths and heights, which values do you want? — Rawling
– Rawling, Commented Oct 23, 2012 at 14:58
Like in SQL you'd have to choose which ones to take after the grouping. Try g.First() to get the first Width or Height in the grouping. — Mikey Mouse
– Mikey Mouse, Commented Oct 23, 2012 at 14:59
(Also the Where clause is redundant - if there're no items with a given label and height, there won't be a group for them anyway.) — Rawling
– Rawling, Commented Oct 23, 2012 at 15:07
So do you want a list/collection of all of the width/heights, do you want the average, first, sum, max, last minimum, or what? — Servy
– Servy, Commented Oct 23, 2012 at 15:23

spender · Accepted Answer · 2012-10-23 15:01:49Z

18

After this

testList
  .GroupBy(i => new { i.Length, i.Label })
  .Where(g => g.Count() >= 1)

you effectively have an IEnumerable<IEnumerable<Test>>. That's a list of lists of dupes. What more do you want?

answered Oct 23, 2012 at 15:01

spender

121k36 gold badges245 silver badges369 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Jon Over a year ago

+1 and thanks for reminding me about compiler support for anonymous types.

Tony Over a year ago

Sorry I think I asked the question without thinking it through. Thanks for the answer though.

Collectives™ on Stack Overflow

How to find duplicate items based on multiple values using LINQ?

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related