Linq to Objects:Distinct + Concatenation

Question

我有一个对象列表,其中9个属性中的8个频繁重复,最后一个属性在整个过程中不同.

使用C#和LINQ对象我想检索前8个属性的(分组)不同列表,其中第9个属性在整个组中连接...

public class MyClass
{
    public int property1 {get;set;}
    public string property2 {get;set;}
    public string property3 {get;set;}
}

我可能有一个列表,如:

var list1 = new List<myClass>
        {
            new myClass {property1 = 1, property2 = "foo", property3 = "This"},
            new myClass {property1 = 1, property2 = "foo", property3 = "is"},
            new myClass {property1 = 1, property2 = "foo", property3 = "a"},
            new myClass {property1 = 1, property2 = "foo", property3 = "test"},
            new myClass {property1 = 1, property2 = "foo", property3 = "value"},
            new myClass {property1 = 2, property2 = "bar", property3 = "Here's"},
            new myClass {property1 = 2, property2 = "bar", property3 = "a"},
            new myClass {property1 = 2, property2 = "bar", property3 = "second"}
        };

我正在努力编写能够生成以下对象列表的最高性能的LINQ表达式:

{
    {property1 = 1, property2 = "foo", newProperty3 = "This is a test value"},
    {property1 = 2, property2 = "bar", newProperty3 = "Here's a second"}
};

有人会介意帮忙吗？

Answer 1

您正在寻找的是GroupBy具有复合键的查询:

list1.GroupBy(x => new { x.property1, x.property2 })
     .Select(g => new 
                    { 
                      property1 = g.Key.property1, 
                      property2 = g.Key.property2, 
                      newProperty3 = string.Join(" ", g.Select(x => x.property3))
                    });