如何将多个列表项组合成一个项？

Question

我创建了一个名为Impacts的类:

public class Impacts {
    public Impacts(string _Source, int _Number, string _Target) { 
        this.Source = _Source; 
        this.Number = _Number; 
        this.Target = _Target; 
    }
}

并创建了这个类的列表:

List<Impacts> ListOfImpacts = new List<Impacts>();

然后,我在创建的列表中添加了项目:

ListOfImpacts.Add(new Impacts("a" , 1 , "b")); //record 1 
ListOfImpacts.Add(new Impacts("c" , 1 , "d")); //record 2 
ListOfImpacts.Add(new Impacts("d" , 1 , "a")); //record 3 
ListOfImpacts.Add(new Impacts("d" , 1 , "a")); //record 4 
ListOfImpacts.Add(new Impacts("d" , 1 , "a")); //record 5

我想把记录3和记录4和记录5结合起来,因为它们具有相同的"Source"="d"和相同的"Target"="a",所以我可以:

new Impacts("d", 3 , "a"); // 3 is the number of iterations of this record 

并删除三个重复的记录.

有人能帮我吗？

Answer 1

var newList = ListOfImpacts.GroupBy(g => new {g.Source, g.Target})
            .Select(g => new Impacts(g.Key.Source, g.Count(), g.Key.Target))
            .ToList();

实例:http://rextester.com/XOIYM52525