Question

如何通过Person中选择的字典值对其进行排序？

示例：“人员”的订单列表由“cars”值降序。

这可能与其中一个奇特的lambda / linq方程有关吗？

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：

结果将是基于每个人的词典中包含的值的新的或重新排序的列表

人 - ＆gt;汽车 - ＆gt; {“volvo”，“34023200”}
人 - ＆gt;汽车 - ＆gt; {“volvo”，“3554000”}
人 - ＆gt;汽车 - ＆gt; {“volvo”，“340050”}

新的或重新排序的列表看起来完全如下：

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

这是一个漂亮的技巧;基本上，字典可以被认为是KeyValuePair的列表＆lt;＆gt;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

现在它在一个列表中，很容易通过LINQ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你需要对Dictionary进行排序和排序 - 这并不是一个真正与字典概念组合在一起的操作（它更适合通过指定键快速访问特定元素）。你写的问题描述似乎很奇怪;你可以为特定的人订购汽车，但是你是否试图找到按价值订购的每个人的每辆车？

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

如果您的意思是按照该人拥有的汽车数量排序

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

如果您的意思是按照该人拥有的第一个（按名称排序）汽车名称排序

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

如果您的意思是按人员拥有的第一个（按号码排序）车号排序

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

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

根据您提供的示例，这可能只是为您完成工作：

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

如何按字典值对对象列表进行排序？

2 个答案: