具有相等集合的组对象 [英] group object with equal collections

问题描述

假设有2个类，人"和宠物".每个人都有1个或更多宠物的集合. 我如何将人"分组到他们共享相同宠物的集合中.

Suppose 2 classes, Person and Pet. Each person has a collection of 1 or more pets. How do i group the Person in to a collection where they share the same pets.

示例:

人1:猫，狗，蜘蛛

人2:猫，蜘蛛，蛇

人3:狗

第4个人:蜘蛛，猫，狗

Person 4: Spider, Cat, Dog

第5个人:狗

我想要的结果是这样:

第1组:第1个人，第4个人

Group 1: Person 1, Person 4

第2组:第3人，第5人

Group 2: Person 3, Person 5

第3组:第2人

我如何使用LINQ实现这一目标?

How do i achieve this using LINQ?

推荐答案

一种方法是从宠物中构建一个可比较的钥匙.例如，此方法将宠物分类，然后将它们组合成一个字符串，并用'|'

One way is to build a comparable key out of the pets. For example, this method sorts the pets then combines them into a single string separated by '|'

private static string GetPetKey(Person x)
{
    return String.Join("|", x.Pets.OrderBy(y => y).ToArray());
}

带宠物的人:蜘蛛"，猫"，狗" 得到密钥:猫|狗|蜘蛛"

A person with the pets: "Spider", "Cat", "Dog" gets the key: "Cat|Dog|Spider"

然后将其用作LINQ分组密钥

Then use that as your LINQ grouping key

var grouped = people.GroupBy(x => GetPetKey(x))

示例实现:

var people = new List<Person>
    {
        new Person
            {
                Id = 1,
                Pets = new[] { "Cat", "Dog", "Spider" }
            },
        new Person
            {
                Id = 2,
                Pets = new[] { "Cat", "Spider", "Snake" }
            },
        new Person
            {
                Id = 3,
                Pets = new[] { "Dog" }
            },
        new Person
            {
                Id = 4,
                Pets = new[] { "Spider", "Cat", "Dog"  }
            },
        new Person
            {
                Id = 5,
                Pets = new[] { "Dog" }
            }
    };

var grouped = people.GroupBy(x => GetPetKey(x)).ToList();
grouped.ForEach(WriteGroup);

输出助手

private static void WriteGroup(IGrouping<string, Person> grouping)
{
    Console.Write("People with " +String.Join(", ",grouping.First().Pets)+": ");
    var people = grouping.Select(x=>"Person "+x.Id).ToArray();
    Console.WriteLine(String.Join(", ", people));
}

输出:

People with Cat, Dog, Spider: Person 1, Person 4
People with Cat, Spider, Snake: Person 2
People with Dog: Person 3, Person 5

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