c# - 如何在 Linq 中对组内的元素进行分组

Question

我有一个 Employee 集合，我想以这样一种方式进行过滤，即只应过滤前两列，并应附加第三列值，最终结果应在一行中

下面是我的代码

List<Employe> Employeecollection = new List<Employe>();

        Employeecollection.Add(new Employe("Employee1", "Dept1","Language1"));
        Employeecollection.Add(new Employe("Employee2", "Dept2", "Language2"));
        Employeecollection.Add(new Employe("Employee3", "Dept3", "Language3"));
        Employeecollection.Add(new Employe("Employee3", "Dept3", "Language3"));
        Employeecollection.Add(new Employe("Employee1", "Dept1", "Language2"));

        foreach (Employe item in Employeecollection.GroupBy(x => new { fName = x.EmpName, lName = x.EmpDept, mName = x.KnownLanguages }).Select(g => g.First()))
        {
            Console.WriteLine(item.EmpName + "   " + item.EmpDept + " " + item.KnownLanguages);
        }

但我想显示如下结果

Employee1 Dept1 Language1,Language2Employee2 Dept2 Language2Employee3 Dept3 Language3

Answer 1

按姓名和部门对员工进行分组，然后为每个员工选择连接的已知语言字符串:

from e in Employeecollection
group e by new { e.Name, e.EmpDept } into g
select new {
   g.Key.Name,
   g.Key.EmpDept,
   Languages = String.Join(",", g.Select(x => x.KnownLanguages))
}

如果您希望结果为单行，则改为执行以下投影:

select String.Format("{0} {1} {2}", 
    g.Key.Name, g.Key.EmpDept, String.Join(",", g.Select(x => x.KnownLanguages)))

顺便说一句，我认为它是一个奇怪的属性名称KnownLanguages，用于包含单一语言的属性