如何在C#中与列表相交? [英] How to intersect list in c#?

问题描述

我在c#中具有以下 Item 对象的列表:

I have following list of Item objects in c#:

public class Item
{
    public int Id { get; set; }
    public List<string> Orders { get; set; }
}

List<Item> item = new List<Item>() { 
               new Item() { Id = 1, Code = 23, Orders = new List<string>() { "A", "B" }},
               new Item() { Id = 2, Code = 24, Orders = new List<string>() { "C", "D" }},
               new Item() { Id = 1, Code = 23, Orders = new List<string>() { "E", "F" }},
               new Item() { Id = 3, Code = 25, Orders = new List<string>() { "G", "H" }}
              };

我要合并ID相同的订单，因此上面列表的输出应为:

I want to concat the Orders whose Id is same, so the output of above list should be:

    { 
      new Item() { Id = 1, Code = 23, Orders = new List<string>() { 'A', 'B', 'E', 'F' },
      new Item() { Id = 2, Code = 24, Orders = new List<string>() { 'C', 'D' },
      new Item() { Id = 3, Code = 25, Orders = new List<string>() { 'G', 'H' }
    };

我如何才能在c#中有效地做到这一点(如果可能，请使用linq)?

How can i do this efficiently in c# ( using linq if possible ) ?

推荐答案

您要根据项目的ID对项目进行分组，然后根据该组的所有Orders创建新序列.

You want to group the items based on their ID, and then create a new sequences based on all of the Orders for that group.

var query = items.GroupBy(item => item.Id)
    .Select(group => new Item
    {
        Id = group.Key,
        Orders = group.SelectMany(item => item.Orders).ToList()
    });

请注意，这不是任何数据的交集.您将获得每个组中所有数据的 union .

Note that this is not the intersection of any data. You're getting the union of all data within each group.

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