List分组和排序

//分组
var ll= lst.GroupBy(x => new { x.Id, x.Name }).Select(x => new
            {
                Key = x.Key,
                Id = x.First().Id,
                Name = x.First().Name,
                Count = x.Sum(s => s.Value)
            });


//排序
List<int> list = new List<int>(); 
list.Sort();// 升序排序 
list.Reverse();// 反转顺序

List<int> list= new List<int>(){5,1,22,11,4}; 
list.Sort((x, y) => x.CompareTo(y));//升序 
list.Sort((x, y) => -x.CompareTo(y));//降序

//定义一个集合
var list = new List<Object>();//这里的Type为对象类型
//假设list已经有数据存进去，根据对象的某个字段升序或降序
var orderInfo = list.OrderByDescending(a => a.ProductID).ToList();//降序
var orderInfo = list.OrderBy(a => a.ProductID).ToList();//升序