C# list pool / remove duplicates

Question

I have got a list which looks like this:

Id: 1
Line1: Microsoft
Line2: Windows
Line3: Server
Line4: null
Line5: null

Id: 2
Line1: Microsoft
Line2: Windows
Line3: Server
Line4: null
Line5: null

Id: 3
Line1: Microsoft
Line2: Windows
Line3: Server
Line4: Development
Line5: null

Now I would like to pool / remove all the duplicates (Id 1 and 2). How is this possible?

I tried something like this:

result = result.DistinctBy(x => x.Line3).ToList();

But then it would also remove Id 3 which is not correctly.

Expected output:

Id: 2              // can also be 1, doesn't matter
Line1: Microsoft
Line2: Windows
Line3: Server
Line4: null
Line5: null

Id: 3
Line1: Microsoft
Line2: Windows
Line3: Server
Line4: Development
Line5: null

What do you mean "pool all the duplicates"? Show your expected output. — MrZander, May 12 '17 at 16:18
Sorry for that, I want to remove them. Look at my edit @MrZander — Tom el Safadi, May 12 '17 at 16:19
Does it matter whether you keep 1 or 2 if they are duplicates? — msitt, May 12 '17 at 16:19
Yes I need to keep one of them, the Id doesn't matter though @msitt — Tom el Safadi, May 12 '17 at 16:20
What about an `IEqualityComparer` on the object in the list, and call `.Distinct()`? — entropic, May 12 '17 at 16:26
http://stackoverflow.com/questions/8560884/how-to-implement-iequalitycomparer-to-return-distinct-values — Magnetron, May 12 '17 at 16:29

score 1 · Accepted Answer · answered May 12 '17 at 16:33

1

A simple method is to create a Tuple as the grouping object.

result = result.GroupBy(r => Tuple.Create(r.Line1, r.Line2, r.Line3, r.Line4, r.Line5))
               .Select(g => g.First())
               .ToList();

I do not have DistinctBy, but this should work:

result = result.DistinctBy(r => Tuple.Create(r.Line1, r.Line2, r.Line3, r.Line4, r.Line5))
               .ToList();

answered May 12 '17 at 16:33

msitt

1,237
12
27

Did it! Thanks boss;) – Tom el Safadi May 12 '17 at 16:48

score 0 · Answer 2 · answered May 12 '17 at 16:39

0

You're on the right track with your DistinctBy you just need to create an anonymous type with all the fields you care about

result = result.DistinctBy(x => new {x.Line1, x.Line2, x.Line3, x.Line4, x.Line5}).ToList();

answered May 12 '17 at 16:39

RobPethi

551
9
27

C# list pool / remove duplicates

2 Answers2