数据结构-集合

集合

• 无序且唯一的数据结构
• Es6 有集合名为set
• set 常用的操作:去重，判断某元素是否在集合中，求交集

去重

const arr1 = [1,1,2,2];
const arr2 = [...new Set(arr1)]

判断元素是否在集合中

const arr1 = [1,1,2,2];
const set = new Set(arr1);
const has = set.has(3);
console.log('has');
console.log(has)//false

求交集&&差集

const arr1 = [1,1,2,2];
const set = new Set(arr1);
const set2 = new Set([2,3]);
const theSame = [...set].filter((item)=>{
  set2.has(item)
})
const deferent = [...set].filter((item)=>{
  !set2.has(item)
})
console.log('theSam1');
console.log(theSame);
console.log('deferent');
console.log(deferent)

const arr1 = [1,1,2,2];
const set = new Set(arr1);
const set2 = new Set([2,3]);
const set3 = [...set].filter((item)=>{
  set2.has(item)
})

set操作

使用Set对象:New add delete has size

迭代Set:多种迭代方法，set与array互转，求交集/差集

add (set对象里面添加元素)

let mySet = new Set();
mySet.add(1);
mySet.add(2);
mySet.add(2);
console.log(mySet);//{1,2}
let o = {a:1,b:2,c:3}
mySet.add(o);
console.log(mySet);//{1,2,value:{a:1,b:2,c:3}}

delete (set对象里面删除元素)

let mySet = new Set();
mySet.add(1);
mySet.add(2);
mySet.add(2);
mySet.delete(2);
console.log(mySet);//{1}

迭代一个Set(循环set)

let mySet = new Set();
mySet.add(1);
mySet.add(2);
for(let item of mySet){
  console.log(item)
}
// 1
// 2
for(let item of mySet.keys()){
  console.log(item)
}
for(let item of mySet.values()){
  console.log(item)
}

Set和Array互转

//1.集合转数组
let mySet = new Set();
let arr1 = [...mySet];
//2.集合转数组
let mySet1 = new Set();
let arr2 = Array.from(mySet1);
//1.数组转集合
let myArra1 = new Set([1,2,3,4]);