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根据数组的键对数组进行分组,并使用组作为索引创建新数组

arrays javascript

Dhiraj · 技术社区 · 8 年前

我试图从一个数组中创建一个新数组,该数组将按键分组,新数组的索引将是旧数组的键,如下所示

旧阵列

Array1
0 :term_id: "1"
   capacity:"11"
   price: "452"
1 :term_id: "2"
   capacity:"33"
   price: "44"
2 :term_id: "1"
   capacity:"1"
   price: "2"

我希望将此阵列按 term_id 因此,新阵列是

新建阵列

Array2
1 :terms >
   0: capacity:"11"
      price: "452"
   1: capacity:"1"
      price: "2"
2 :terms >
  0:  capacity:"33"
      price: "44"

如您所见,在新数组中,数组按term\u id的索引分组,其中还有另一个arary及其内容

我试过使用 groupBy 方法,但我无法保留旧数组的索引

5 回复 | 直到 8 年前

Ele 8 年前

您可以使用该功能 reduce 分组并生成所需的输出。

var Array1 = [{  term_id: "1",  capacity: "11",  price: "452"}, {  term_id: "2",  capacity: "33",  price: "44"}, {  term_id: "1",  capacity: "1",  price: "2"}];

var result = Object.values(Array1.reduce((a, {term_id, capacity, price}) => {
  (a[term_id] || (a[term_id] = {terms: []})).terms.push({capacity, price});
  return a;
}, {}));

console.log(result);

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Hassan Imam Ravi kant 8 年前

您可以使用 array#reduce 根据对对象数组进行分组的步骤 term_id 在对象中,然后使用 Object.values() 。

var data = [{ term_id: "1", capacity: "11", price: "452" }, { term_id: "2", capacity: "33", price: "44" }, { term_id: "1", capacity: "1", price: "2" }],
    result = Object.values(data.reduce((r,{term_id, capacity, price})=> {
      r[term_id] = r[term_id] || [];
      r[term_id].push({capacity, price});
      return r;
    },{}));
console.log(result);

yajiv 8 年前

您可以使用 reduce 数组的。原型

x = [{term_id:"1",capacity:"11",price:"452"},{term_id:"2",capacity:"33",price:"44"},{term_id:"1",capacity:"1",price:"2"}];

y = x.reduce((n, e) => {
            var clone = Object.assign({}, e);  //creating duplicate object
            delete clone.term_id;              //deleteing term_id property from clone object
            if (!n[e.term_id]) {
                n[e.term_id] = [];
            }
            n[e.term_id].push(clone);    //pushing clone instead of e as e contains term_id which we don't need in result
            return n;
        }, {});
   
console.log(y);

kpie 8 年前

如果您想使用循环。。。将所有数据复制到结果中有点浪费内存,我认为更好的做法是生成所需的数据并保留任何已经存在的值,但这可能会导致更糟糕的代码-_-

function idxOfGroupBy(hl,key){
let ret = [];
for(var k = 0; k < hl.length; k++){
	try{
		ret[hl[k][key]].push(k);
	}catch(err){
		ret[hl[k][key]] = [];
		ret[hl[k][key]].push(k);
	}
}
return(ret);
}

let hashList = [{at1:"1",atr2:"."},{at1:"2",atr2:".."},{at1:"1",atr2:"..."}];
let groupIdxs = idxOfGroupBy(hashList,"at1");
console.log(groupIdxs);

Jonas Wilms 8 年前

只需使用哈希表进行分组:

 const result = [], hash = {};

 for(const obj of array) {
   if(hash[obj.term_id]) {
     hash[obj.term_id].push(obj);
   } else {
     result.push(hash[obj.term_id] = [obj]);
   }
 }