如何从基于另一个列表的元素和条件的一个列表中删除元素？

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();