c#集合去重&排序常用方法

我会带着你远行 2024-03-24 10:58 36阅读 0赞

## list与数组转Hashset&SortedSet ##

//创建hashset去重
    var hashSet = new HashSet<int>(){1,1,2,2};
    Console.WriteLine("HashSet:"+String.Join(", ", hashSet));
    // HashSet:1, 2
    
    //创建list包含重复元素
    var ints = new List<int>{1,1,3,3,2,2};
    //创建数组转HashSe包含重复元素
    int[] numbers = { 1, 1, 3, 2, 2 };
    
    
    //list转HashSet
    var set = ints.ToHashSet();
    Console.WriteLine("List转HashSet:"+String.Join(", ", set));
    //List转HashSet:1, 3, 2
    
    var immutableSortedSet = ints.ToImmutableSortedSet();
    Console.WriteLine("immutableSortedSet:"+String.Join(", ", immutableSortedSet));
    
    
    //数组转HashSet
    var hashSet1 = new HashSet<int>(numbers);
    Console.WriteLine("数组转HashSet:"+String.Join(", ", hashSet1));
    //数组转HashSet:1, 3, 2
    
    //数组转SortedSet
    var sortedSet = new SortedSet<int>(numbers);
    Console.WriteLine("数组转SortedSet:"+String.Join(", ", sortedSet));
    //数组转SortedSet:1, 2, 3

## 当hashset存的是类时 ##

创建饮料类

public class Drink
    {
        public String Name { get; set; }
        
        public int Price { get; set; }
    }

new一个HashSet存放饮料类

![7b55048fbf934f0f84f21f36de81ce12.png][]

打印出来并未去重

### 自定义比较规则 ###

public class DrinkEquelityCompare : IEqualityComparer<Drink>
    {
        public bool Equals(Drink x, Drink y)
        {
            //Name相等去除
            return x.Name == y.Name;
        }
    
        public int GetHashCode(Drink obj)
        {
            return base.GetHashCode();
        }
    }

重新new一个类

//var drinks = new HashSet<Drink>(new DrinkEquelityCompare());
    drinks.Add(new Drink{Name = "牛奶",Price = 19});
    drinks.Add(new Drink{Name = "牛奶",Price = 20});
    drinks.Add(new Drink{Name = "茉莉花茶",Price = 19});
    drinks.Add(new Drink{Name = "茉莉花茶",Price = 19});
    foreach (var drink in drinks)
    {
        Console.WriteLine(drink.Name+drink.Price);
    }

此时打印以及去除掉Name相同的值了

![11c159e167ad4cdfbecd29686504faa5.png][]

## SortedSet存放类时自定义排序规则 ##

还是用刚刚的Drink类

public class DrinkCompare : IComparer<Drink>
    {
        public int Compare(Drink x, Drink y)
        {
            //返回值>0 x大；  返回值=0，一样大；  返回值小于0，y大
            return x.Price-y.Price;
        }
    }

添加数据

SortedSet<Drink> sorted = new(new DrinkCompare());
    sorted.Add(new Drink{Name = "橘汁",Price = 19});
    sorted.Add(new Drink{Name = "牛奶",Price = 20});
    sorted.Add(new Drink{Name = "茉莉花茶",Price = 17});
    sorted.Add(new Drink{Name = "可乐",Price = 21});
    
    foreach (var drink in sorted)
    {
        Console.WriteLine(drink.Name+drink.Price);
    }

打印出来的数据以及按照price进行排序了

![090a24a84a094b35b1d9c6ea87379a2e.png][]

[7b55048fbf934f0f84f21f36de81ce12.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/24/6401188cf1c64e458b4e98fede9ca76c.png
[11c159e167ad4cdfbecd29686504faa5.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/24/816d30dcec9345b7ae0c049e2f74a608.png
[090a24a84a094b35b1d9c6ea87379a2e.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/24/f99240a5006a49559ad6af9603de0d68.png