根据列表中的元素对同一对象进行分组 [英] Grouping the same object according to the elements of their lists

问题描述

我有以下类型为Application的对象的列表，如下所示:

I have following list of the objects of type Application, which looks like:

public class Application
    {
        public int AppId { get; set; }
        public List<Question> Questions { get; set; }
    }

我想做的就是将它们映射到Section类型的对象，如下所示:

What I want to do is to map them to object of type Section looking like:

public class Section
       {
            public List<int> AppIds { get; set; }
            public List<Question> Questions { get; set; }
        }

通过按照以下规则将它们分组:在包含这些问题的AppId列表下收集所有相同的问题.示例输入和输出:

by grouping them according to following rule: gather all the same questions under the lists of AppIds, which contain these questions. Exemplary Input and Output:

Input: A1(Q1,Q2,Q3), A2(Q1,Q2), A3(Q1,Q3), A4(Q1). 
Output: A1,A2,A3,A4(Q1), A1,A2(Q2), A1,A3(Q3)

有可能在LINQ中做到吗?还是我必须自己编写逻辑?

Is that possible to do it in LINQ? Or I have to write logic on my own?

推荐答案

也许有更简单的方法，但这是我编写的第一个LINQ查询，至少应该足以使您入门.首先，我将您的问题和appid弄平，然后按问题重新组合，然后按问题列出您的appid.请注意，您必须先填充List应用程序，然后该程序才能运行.

Maybe there is a simpler way, but this is the first LINQ query I wrote and should be enough to at least get you started. First I flattened out your questions and appids, then I regrouped by questions and listed your appids by question instead. Note that you'll have to populate your List of applications before this will run.

List<Application> app = new List<Application>();
var output = (from a in app.SelectMany(p => p.Questions.Select(z => new {z, p.AppId})
group a.AppId by new 
{
a.Questions
} into combined
select new 
{
combined.Key.Questions,
combined.ToList()
});

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