如何按字典值对对象列表进行排序？

Question

我如何根据 Person 中选定的字典值对其进行排序？

示例：“人”列表按“汽车”值降序排列。

这可以用那些奇特的 lambda/linq 方程之一来实现吗？

public class People 
{
    List<Person> Persons { get; set; }
}

public class Person
{
    public Dictionary<string, string> cars { get; set; } 
    public Dictionary<string, string> houses { get; set; } 
    public Dictionary<string, string> banks { get; set; }
}

................

People people = new People();

people.Persons = new List<Person> 
{
    new Person 
    {
        cars = new Dictionary<string, string> { { "volvo", "340050" }, { "bmw", "50545000" } }, 
        houses = new Dictionary<string, string> { { "mansion", "100040000" },{ "cardboard box", "112" } },
        banks = new Dictionary<string, string> { { "swiss", "12500330000" }, { "camen", "12000000" } }
    }, 
    new Person 
    {
        cars = new Dictionary<string, string> { { "volvo", "34023200" }, { "bmw", "5003300" } }, 
        houses = new Dictionary<string, string> { { "mansion", "1000330000" },{ "cardboard box", "277" } },
        banks = new Dictionary<string, string> { { "swiss", "12500044000" }, { "camen", "12000000" } }
    }, 
    new Person 
    {
        cars = new Dictionary<string, string> { { "volvo", "3554000" }, { "bmw", "50023200" } }, 
        houses = new Dictionary<string, string> { { "mansion", "1006600000" },{ "cardboard box", "244" } },
        banks = new Dictionary<string, string> { { "swiss", "125000544000" }, { "camen", "12000777000" } }
    }
};

编辑/示例结果：

结果将是一个新的或重新排序的列表，基于每个人的字典中包含的值

Person ->汽车 -> {“沃尔沃”，“34023200”}
人->汽车 -> {“沃尔沃”，“3554000”}
人->汽车 -> { "volvo", "340050" }

新的或重新排序的列表将如下所示：

people.Persons = new List<Person> 
{
    new Person 
    {
        cars = new Dictionary<string, string> { { "volvo", "34023200" }, { "bmw", "5003300" } }, 
        houses = new Dictionary<string, string> { { "mansion", "1000330000" },{ "cardboard box", "277" } },
        banks = new Dictionary<string, string> { { "swiss", "12500044000" }, { "camen", "12000000" } }
    },
    new Person 
    {
        cars = new Dictionary<string, string> { { "volvo", "3554000" }, { "bmw", "50023200" } }, 
        houses = new Dictionary<string, string> { { "mansion", "1006600000" },{ "cardboard box", "244" } },
        banks = new Dictionary<string, string> { { "swiss", "125000544000" }, { "camen", "12000777000" } }
    },
    new Person 
    {
        cars = new Dictionary<string, string> { { "volvo", "340050" }, { "bmw", "50545000" } }, 
        houses = new Dictionary<string, string> { { "mansion", "100040000" },{ "cardboard box", "112" } },
        banks = new Dictionary<string, string> { { "swiss", "12500330000" }, { "camen", "12000000" } }
    }
};

Answer 1

这是一个巧妙的技巧；基本上，字典可以被认为是 KeyValuePair<> 的列表。对象。

Dictionary<int, string> myDictionary = new Dictionary<int, string>();
foreach(var item in myDictionary)
// item is a KeyValuePair<int, string>, enumerated in order of their insertion into the dictionary

既然它在列表中，就可以很容易地通过 LINQ 进行排序：

Dictionary<int, string> sample = new Dictionary<int, string>
{
   { 1, "Sample" },
   { 2, "Another Sample" }
};

var orderedList = sample.OrderBy(x => x.Value).ToList();

当然，更大的问题是为什么您需要对字典进行排序和排序 - 这并不完全是一个真正与字典概念分组的操作（它是更多用于通过指定键快速访问特定元素）。你写的问题描述看起来很奇怪；您可以为特定的人订购汽车，但是您是否想按价值从每个人那里找到每辆车？

这也很容易做到：

List<PersonCarDetails> allStuff = new List<PersonCarDetails>();

foreach(var person in persons)
   allStuff.AddRange(person.Cars.Select(x => new PersonCarDetails { PersonId = person.Id, CarName = x.Key, CarId = x.Value }).ToList());

 // allStuff now contains a list of PersonCarDetails, and then you can order that:

 var orderedList = allStuff.OrderBy(x => x.CarId).ToList();

Answer 2

如果您的意思是按此人拥有的汽车数量排序

var result = Person.OrderByDescending(x => x.cars.Count);

如果您的意思是按此人拥有的第一个（按名称排序）汽车名称排序

var result = Person.OrderByDescending(x => x.cars.Keys.OrderBy(y => y.Key).FirstOrDefault());

如果您的意思是按此人拥有的第一个（按数字排序）汽车号码

var result = Person.OrderByDescending(x => x.cars.Keys.OrderBy(y => y.value).FirstOrDefault());

排序示例输出可以很好地阐明您实际想要排序的内容，因为 cars 是一个列表，而不仅仅是一个元素。

---

根据您提供的示例，这可能适合您：

var result = Person.OrderByDescending(x => x.cars.Values.FirstOrDefault());