How to Remove elements from one List based another list's element and condition?

Question

How to remove list items from list1 which mats condition with list2 items using LINQ without duplicates

I know how to do it in simple foreach way but i want the same using Linq style single line code.

How to do it using Linq ?

Input list

list1 = new List(){new object{id = 40},new object{id = 50},new object{id = 60}}
list2 = new List(){new object{id = 400},new object{id = 50},new object{id = 600}}

Expected Output should from list1

new object{id = 40},new object{id = 60}

Answer 1

您可以删除以下元素：

list1.RemoveAll(item => list2.Any(item2 => item.Key == item2.Key))

Answer 2

尝试这个：

var list = list1.RemoveAll(l => list2.Contains(l));

Answer 3

In other perspective,

var list1 = Provider.FillList<SomeType>();
var list2 = Provider.FillList<SomeType>();
list1.RemoveAll(n=> list2.Exists(o=> o.Key == n.Key));

Answer 4

You can also try

list1.addRange(list2)
then next line would be a simple list1.Distinct(X=>x.Key1).ToList();

OR simples would be

list1.Except(list2,IEqualityComparer);

You would need to implement the equals method for this to work though.

Another way would be to implement the Union

var result = List1.Union(List2, myEqualityComparer);

which uses the same logic as the except one, there are a few ways to cheat the endresult using link, most of them inefficient and take long to compute

Answer 5

I would solve this with a Join statement:

var l = list1.Join(list2, outer => outer.Key, inner => inner.Key, (inner, outer) => outer);

where outer is list1 and inner is list2. The result is a list comprising all elements with the same Key , assuming that Key is a property of the elements.

Answer 6

The following code worked for me:

var list1 = new List<a> { new a { id = 40 }, new a { id = 50 }, new a { id = 60 } }; 
var list2 = new List<a> { new a { id = 400 }, new a { id = 50 }, new a { id = 600 } }; 

var exceptedItems=list1.Select(x=>x.id).Except(list2.Select(y=>y.id)).ToList();