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问题描述

我有一个

 公共类公司
{
公众诠释ID {搞定;组; }
公共字符串的标题{搞定;组; }
公共字符串的地址{搞定;组; }
公共字符串城市{搞定;组; }
公共字符串拉链{搞定;组; }
公开名单<串GT;电话{搞定;组; }
公开名单<串GT;类别{搞定;组; }
}

和我有一个泛型列表其中包含



公开名单<公司>公司=新的List<公司>();



我想要做的两件事情:




  1. 获得类别的不同列表

  2. 得到每类企业的总数



我想我管理的第一件事:



Companies.SelectMany(C =以及c .categories).Distinct()
请告诉我,如果你认为有什么不妥。



我想第二个步骤像这样:
Companies.SelectMany(C => c.categories)。凡(C =以及c ==类别).Count之间的()
,但林不知道这是很合适。


解决方案

  1. 正确


  2. 您需要拼合列表进入(公司类别)对,然后按类别组:

     从公司公司
    从类别中company.Categories
    组公司类别为G
    选择新{类别= g.Key,计数= g.Count ()}






    修改:如果你想找出多少企业是在一个给定的类别,你可以写

      Companies.Count(三= GT; c.Categories.Contains(类别名))



i have a Class:

public class Company
{
    public int id { get; set; }
    public string title { get; set; }
    public string address { get; set; }
    public string city { get; set; }
    public string zip { get; set; }
    public List<string> phones { get; set; }
    public List<string> categories { get; set; }
}

and i have a Generic List which contains that Class:

public List<Company> Companies = new List<Company>();

i want to do two things:

  1. get a distinct list of the categories
  2. get a total count of companies per category

i think i managed to the the first thing:

Companies.SelectMany(c => c.categories).Distinct()please tell me if you think anything is wrong with that.

i tried the second step as so:Companies.SelectMany(c => c.categories).Where(c=>c == Category).Count()but im not sure that is really right.

解决方案
  1. Correct

  2. You need to flatten the list into (company, category) pairs, then group by category:

    from company in Companies
    from category in company.Categories
    group company by category into g
    select new { Category = g.Key, Count = g.Count() }
    


    EDIT: If you want to find out how many companies are in a single given category, you can write

    Companies.Count(c => c.Categories.Contains(categoryName))
    

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10-27 03:54