C# 使用linq或lambda表达式进行对象分组

我有一个要转换为另一个对象列表的对象列表

第一个对象如下所示：

    private class ObjectOne
    {
        public string Name { get; set; }
        public string Item{ get; set; }
    }

还有一个像这样的

public class ObjectTwo
{
    public string Name { get; set; }
    public IEnumerable<string> Items{ get; set; }
}

将生成以下两个对象列表：

"Name One", {"Item One", "Item Two"}
"Name Two", {"Item Three"}

---

您可以使用

group by

LINQ操作符来实现这一点：

var obj2List =
    from o in list
    group o by o.Name into g
    select new ObjectTwo() {Name = g.Key, Items = g.Select(x => x.Item)};

---

使用GroupBy Linq操作符。然后，为每个分组选择键（用于分组的键），并将每个分组的项目转换为列表

var oneList = new List<ObjectOne>
              {
                new ObjectOne {Name = "Name One", Item = "Item One"},
                new ObjectOne {Name = "Name One", Item = "Item Two"},
                new ObjectOne {Name = "Name Two", Item = "Item Three"}
              };

var twoList= oneList.GroupBy(x => x.Name)
                    .Select (x => new ObjectTwo 
                                   {
                                      Name = x.Key, 
                                      Items = x.Select(t => t.Item)
                                   });

var oneList=新列表
{
新对象一{Name=“Name One”，Item=“Item One”}，
新对象一{Name=“Name One”，Item=“Item Two”}，
新对象一{Name=“Name Two”，Item=“Item Three”}
};
var twolest=oneList.GroupBy（x=>x.Name）
.选择（x=>newobjecttwo
{
Name=x.Key，
Items=x.Select（t=>t.Item）
});

+1表示不使用查询理解语法。如果您只写“n=>”而不是“one=>”，则会是+2:）

var oneList = new List<ObjectOne>
              {
                new ObjectOne {Name = "Name One", Item = "Item One"},
                new ObjectOne {Name = "Name One", Item = "Item Two"},
                new ObjectOne {Name = "Name Two", Item = "Item Three"}
              };

var twoList= oneList.GroupBy(x => x.Name)
                    .Select (x => new ObjectTwo 
                                   {
                                      Name = x.Key, 
                                      Items = x.Select(t => t.Item)
                                   });