LINQ查询来获取列表中的不同值 [英] Linq query to get the distinct values in a list

问题描述

想这是我的成员类

 类会员
 {
公共字符串categoryId {搞定;组; } 
公共字符串MemberName {搞定;组; } 
公众诠释距离{搞定;组; } 
} 
  

和，这是清单。

  VAR名单=新名单，LT;会员>（）; 
 list.Add（新{=类别ID01，MemberName =安迪距离= 3}）; 
 list.Add（新{=类别ID02，MemberName =约翰距离= 5}）; 
 list.Add（新{=类别ID01，MemberName =马修距离= 7}）; 
 list.Add（新{=类别ID03，MemberName =巴卡拉距离= 2}）; 
  

任何人都可以请建议逻辑/ LINQ查询来获取具有最短距离不同/独特的categoryID名单

的

输出应该是：

  list.Add（新{=类别ID01，MemberName =安迪距离= 3}）; 
 list.Add（新{=类别ID02，MemberName =约翰距离= 5}）; 
 list.Add（新{=类别ID03，MemberName =巴卡拉距离= 2}）; 
  

解决方案

这应该给你你需要什么：

  VAR分组= list.GroupBy（项目=> item.CategoryId）; 
 VAR最短= grouped.Select（GRP => grp.OrderBy（项目=> item.Distance）。首先（））; 
  

据第一组与同一的CategoryId ，然后选择从每个组（由距离排序）第一。

Suppose this is my member class

class Member 
{
    public string CategoryId { get; set; }
    public string MemberName { get; set; }
    public int Distance { get; set; }
}

And, this is list.

var list = new List<Member>();
list.Add(new { CategoryId = "01", MemberName="andy" Distance=3});
list.Add(new { CategoryId = "02", MemberName="john" Distance=5});
list.Add(new { CategoryId = "01", MemberName="mathew" Distance=7});
list.Add(new { CategoryId = "03", MemberName="bakara" Distance=2});

Can anyone please suggest the logic/ linq query to get the List having distinct/unique categoryID with Shortest distance.

The output should be :

list.Add(new { CategoryId = "01", MemberName="andy" Distance=3});
list.Add(new { CategoryId = "02", MemberName="john" Distance=5});
list.Add(new { CategoryId = "03", MemberName="bakara" Distance=2});

解决方案

This should give you what you need:

var grouped = list.GroupBy(item => item.CategoryId);
var shortest = grouped.Select(grp => grp.OrderBy(item => item.Distance).First());

It first groups the items with the same CategoryId, then selects the first from each group (ordered by Distance).

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