LINQ删除重复项和结果项以具有数量总和 [英] LINQ Remove duplicates and result item to have sum of quantities

问题描述

我只是想检查是否有使用LINQ更快的方法来通过ID从重复项中删除列表，但是结果列表项将具有某些其他属性的总和(在这种情况下为Price).例如:

I just want to check if there is quicker way using LINQ to have list removed from duplicates by id, but in result list item will have sum of some other property (in this case Price). For example:

开始列表:

List<Item> a = new List<Item>
{
   new Item {Id = 1, Name = "Item1", Code = "IT00001", Price = 100},
   new Item {Id = 2, Name = "Item2", Code = "IT00002", Price = 200},
   new Item {Id = 3, Name = "Item3", Code = "IT00003", Price = 150},
   new Item {Id = 1, Name = "Item1", Code = "IT00001", Price = 100},
   new Item {Id = 3, Name = "Item3", Code = "IT00003", Price = 150},
   new Item {Id = 3, Name = "Item3", Code = "IT00004", Price = 250}
};

结果列表将是:

List<Item> a = new List<Item>
{
  new Item {Id = 1, Name = "Item1", Code = "IT00001", Price = 200},
  new Item {Id = 2, Name = "Item2", Code = "IT00002", Price = 200},
  new Item {Id = 3, Name = "Item3", Code = "IT00003", Price = 550}
};

推荐答案

var filteredList = a.GroupBy(e => e.Id).Select(g =>
{
     var item = g.First();
     return new Item
     {
         Id = item.Id,
         Name = item.Name,
         Code = item.Code,
         Price = g.Sum(e => e.Price)
     };
}).ToList();

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