根据来自不同类的计数对对象列表进行降序排序

Question

我被困在这个问题上，我需要根据其他列表进行降序排序。 l_lstNames 需要按年龄降序更新。

public class Test
{
    public String Name;
    public Int32 Age;
}

List<String> l_lstNames = new List<String> { "A1", "A3", "A2", "A4", "A0" };

List<Test> l_lstStudents = new List<Test> 
{ 
    new Test { Age = 33, Name = "A0" }, 
    new Test { Age = 10, Name = "A1" }, 
    new Test { Age = 50, Name = "A2" }, 
    new Test { Age = 8,  Name = "A3" }, 
    new Test { Age = 25, Name = "A4" }, 
};

// Output
List<String> l_lstNames = new List<String> { "A2", "A0", "A4", "A1", "A3" };

找到几个相同的样本，但与我正在寻找的不匹配。谢谢你的帮助。

Answer 1

使用Name 到Age 的映射创建Dictionary<string, int>，并在order 方法中使用它：

var dict = students.ToDictionary(x => x.Name, x => x.Age);

var ordered = source.OrderByDescending(x => dict[x.Name]).ToList();

或者您可以只订购students 收藏然后选择Name only：

var ordered = students.OrderByDescending(x => x.Age)
                      .Select(x => x.Name)
                      .ToList();

Answer 2

如果您只想按降序排列名称：

var sorted = l_lstStudents           // From the list of students
    .OrderByDescending(l => l.Age)   // with the oldest student first
    .Select(s => s.Name)             // give me just the names
    .ToList();                       // in a list!

Answer 3

我想这就是你要找的东西

List<String> l_lstNames1 = (from student in l_lstStudents
                          where l_lstNames.Any(a => student.Name == a)
                          orderby student.Age descending
                          select student.Name ).ToList();

或

List<String> l_lstNames2 = l_lstStudents.OrderByDescending(a => a.Age)
                                .Where(a => l_lstNames.Any(b => b == a.Name))
                                .Select(a => a.Name).ToList();