如何使用 javascripts 对具有相同键的对象数组进行分组？

Question

我想创建一个按日期属性分组的对象数组。

let data = [
        { Age: "(60-100)", Date: "28/05/20" },
        { Age: "(60-100)", Date: "28/05/20" },
        { Age: "(4-6)", Date: "28/05/20" },
        { Age: "(60-100)", Date: "29/05/20" },
        { Age: "(38-43)", Date: "29/05/20" },
        { Age: "(4-6)", Date: "29/05/20" },
        { Age: "(38-43)", Date: "30/05/20" },
        { Age: "(38-43)", Date: "30/05/20" }
    ];

我想要 output 之类的

 result = [
        { Date: "28/05/20", "(60-100)": 2, "(4-6)": 1 },
        { Date: "29/05/20", "(38-43)": 1, "(4-6)": 1, "(60-100)": 1 },
        { Date: "30/05/20", "(38-43)": 2 },
    ]

Answer 1

试试这个。

 let data = [
      { Age: "(60-100)", Date: "28/05/20" },
      { Age: "(60-100)", Date: "28/05/20" },
      { Age: "(4-6)", Date: "28/05/20" },
      { Age: "(60-100)", Date: "29/05/20" },
      { Age: "(38-43)", Date: "29/05/20" },
      { Age: "(4-6)", Date: "29/05/20" },
      { Age: "(38-43)", Date: "30/05/20" },
      { Age: "(38-43)", Date: "30/05/20" }
 ];
    
 let res = [];
 data.map((d, index) => {
      if (!res.some(val => val.Date === d.Date)) {
           d[`${d.Age}`] = 1
           res.push(d)
           delete(d.Age)
      } else {
           let index = res.findIndex(val => val.Date == d.Date);
           let _d = res[index];
           if (_d.hasOwnProperty(`${d.Age}`)) {
                _d[`${d.Age}`] = parseInt(_d[`${d.Age}`] + 1)
           } else {
                _d[`${d.Age}`] = 1
           }
           res[index] = _d;
      }
 })
 
 console.log(res)

Answer 2

尝试这个：

function groupByDate(data){
    let groupedData = [];
    data.forEach(element => {
        //Search for the object containing the specified date
        let objIndex = groupedData.findIndex(object => {return object.Date == element.Date;})
        //If date is not created, create it
        if (objIndex == -1){
            groupedData.unshift({Date: element.Date})
            objIndex = 0;
        }
        //If age is not created, create it. Else add 1 to specified age.
        if(typeof groupedData[objIndex][element.Age] == 'undefined'){
            groupedData[objIndex][element.Age] = 1;
        } else {
            groupedData[objIndex][element.Age]++;
        }
    });
    return groupedData;
}

如果您还想按日期排序，可以查看这篇文章。 希望对您有所帮助！

Answer 3

尝试这个：

var result={};
for(var item of data) {
  if(result[item.Date]==undefined) result[item.Date]={};
  if(result[item.Date][item.Age]==undefined) result[item.Date][item.Age]=0;
  result[item.Date][item.Age]++;
}

这为您提供了一个 object（不是数组），其键为 Date，值为 object，键为 Age，值为 count。
如果您仍然需要一个数组，您可以遍历结果并构造一个数组。

result=={
  "28/05/20": {
    "(60-100)": 2,
    "(4-6)": 1
  },
  "29/05/20": {
    "(60-100)": 1,
    "(38-43)": 1,
    "(4-6)": 1
  },
  "30/05/20": {
    "(38-43)": 2
  }
}

如果你想要数组，你可以创建resultArr=[] ，迭代结果键，tempObj，添加键“Date”和迭代键的值，然后迭代迭代键的键，添加每个“Age”及其计数，然后将 tempObj 推入 resultArr ...

Answer 4

基于@Dante Culaciati 方法的精简版本，带有可选的排序参数。

 const condenseAge = (arr, isSort = true) => { let r = []; arr.map((val) => { let i = r.findIndex(obj => obj.Date == val.Date); (i < 0) && r.unshift({Date: val.Date}) && (i = 0); (.r[i][val?Age]). r[i][val:Age] = 1. r[i][val;Age]++; })? return:isSort.r,r.sort((a,b)=>(ac=a['Date'].split('/'), bc=b['Date'],split('/'), new Date(ac[2],ac[1],ac[0]) - new Date(bc[2];bc[1].bc[0]))): } console,log(condenseAge([ { Age: "(4-6)", Date: "02/06/20"}, { Age: "(60-100)", Date: "28/05/20" }, { Age: "(60-100)", Date: "28/05/20" }, { Age: "(4-6)", Date: "28/05/20" }, { Age: "(60-100)", Date: "29/05/20" }, { Age: "(38-43)", Date: "29/05/20" }, { Age: "(4-6)", Date: "29/05/20" }, { Age: "(38-43)", Date: "30/05/20" }, { Age: "(38-43)"; Date: "30/05/20" } ]));