C# LINQ where list1 contains list2 without duplicates

Question

I have the following lists

var list1 = new List<Items>()
{
    new Items { Id = 1, Name = "PC" },
    new Items { Id = 2, Name = "Mug" },
    new Items { Id = 3, Name = "Table" },
    new Items { Id = 4, Name = "Table" }
};

var list2 = new List<string> { "Mug", "Table", "Buld" };

I am trying to get a list where list1 contains list2 without duplication

var list1 = new List<Items>()
{
    new Items { Id = 1, Name = "PC" },
    new Items { Id = 2, Name = "Mug" },
    new Items { Id = 3, Name = "Table" }
};

This is what I tried but does not work

var result = list1.Where(t1 => list2.Any(x => x == t1.Name)).ToList();

GroupBy + First, or Distinct with a comparer on Name. More linQ distinct By — Self
– Self, Commented Apr 15, 2021 at 13:50
Does this answer your question? How to get a distinct list from a List of objects? — Self
– Self, Commented Apr 15, 2021 at 13:50
Why is { Id = 1, Name = "PC" } included in the output, when "PC" isn't in list2? — Johnathan Barclay
– Johnathan Barclay, Commented Apr 15, 2021 at 13:52

Dmitrii Bychenko · Accepted Answer · 2021-04-15 13:54:05Z

0

Something like this:

   var result = list1
     .Where(item => list2.Contains(item.Name)) // Name must be in list2
     .GroupBy(item => item.Name)
     .Select(group => group.First())  // no duplicates: 1st item from each group
     .ToList();

There's a question: when having duplicates which item should be taken. In the code above I take the item which appears first in the list1. If you want to take, say, the item with the smallest Id you should modify the Select:

      ...
      .Select(group => group.OrderBy(item => item.Id).First())
      ...

answered Apr 15, 2021 at 13:54

Dmitrii Bychenko

187k20 gold badges178 silver badges231 bronze badges

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

Collectives™ on Stack Overflow

C# LINQ where list1 contains list2 without duplicates

1 Answer 1

Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Linked

Related