用相同的键动态合并对象数组

Question

我希望用相同的键动态合并多个对象的单个数组。数据的一个例子是：

var data = [{
  ReportTime: "30 Apr 2017BDT",
  Rate: "1.00000",
  AvgGrowth: "0.0"
}, {
  ReportTime: "30 Apr 2017BDT",
  Rate: "0.01107",
  AvgGrowth: "0.1"
}, {
  ReportTime: "29 Apr 2017BDT",
  Rate: "1.00000",
  AvgGrowth: "0.0"
}, {
  ReportTime: "29 Apr 2017BDT",
  Rate: "0.01107",
  AvgGrowth: "-0.5"
}]

我想生成这样的数据

newData = [{
  "30 Apr 2017BDT",
  "1.00000",
  "0.0",
  "0.01107",
  "0.1"
}, {
  "29 Apr 2017BDT",
  "1.00000",
  "0.0",
  "0.01107",
  "-0.5"
}];

我需要一个建议或帮助如何解决这个问题。

Answer 1

您的预期输出看起来不是一个有效的JS。但是，您可以通过使用.reduce()、.map()和Object.entries()等几种方法迭代数组来获得数组。

​

const data = [
  {ReportTime: "30 Apr 2017BDT", Rate: "1.00000", AvgGrowth: "0.0"},
  {ReportTime: "30 Apr 2017BDT", Rate: "0.01107", AvgGrowth: "0.1"},
  {ReportTime: "29 Apr 2017BDT", Rate: "1.00000", AvgGrowth: "0.0"},
  {ReportTime: "29 Apr 2017BDT", Rate: "0.01107", AvgGrowth: "-0.5"}
];

const result = Object.entries(
  data.reduce((r, {ReportTime, ...rest}) => {
    r[ReportTime] = (r[ReportTime] || []).concat(Object.values(rest));
    return r;
  }, {})
).map(([k, v]) => [k, ...v]);

console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

​

下面是使用es5(旧的)语法的另一种方法：

​

var data = [
  {ReportTime: "30 Apr 2017BDT", Rate: "1.00000", AvgGrowth: "0.0"},
  {ReportTime: "30 Apr 2017BDT", Rate: "0.01107", AvgGrowth: "0.1"},
  {ReportTime: "29 Apr 2017BDT", Rate: "1.00000", AvgGrowth: "0.0"},
  {ReportTime: "29 Apr 2017BDT", Rate: "0.01107", AvgGrowth: "-0.5"}
];
var key = 'ReportTime';

var reducer = function(data, key) {
  var result = [];
  var map = {};
  
  data.forEach(function(o, i) {
    map[o[key]] = map[o[key]] || [];
    
    for(var k in o) {
      if(!(k === key)) { map[o[key]].push(o[k]); }
    };
  });
  
  for(var j in map) {
    result.push([].concat(j, map[j]));
  };
  
  return result;
};

console.log(reducer(data, key));

​

Answer 2

可以通过ReportTime将值归为组。

​

const data = [{ ReportTime: "30 Apr 2017BDT", Rate: "1.00000", AvgGrowth: "0.0"}, { ReportTime: "30 Apr 2017BDT", Rate: "0.01107", AvgGrowth: "0.1"}, { ReportTime: "29 Apr 2017BDT", Rate: "1.00000", AvgGrowth: "0.0"
}, { ReportTime: "29 Apr 2017BDT", Rate: "0.01107", AvgGrowth: "-0.5"}]

const merged = data.reduce((op, inp) => {
  let key = inp.ReportTime
  op[key] = op[key] || []
  op[key].push(inp)
  return op
}, Object.create(null))

console.log(merged)

​

Answer 3

我认为，如果将group变成具有维护速率和AvgGrowth的对象，将很有帮助。

检查项目，构建一个带有键的对象，其名称为"ReportTime“。当ReportTime已经存在于对象中时，只需更新速率和AvgGrowth。迭代之后，获取上述对象的Object.values()作为数组。

​

const update = data => {
  const res = {};
  data.forEach(item => {
    if (!res[item.ReportTime]) {
      res[item.ReportTime] = {
        ReportTime: item.ReportTime,
        Rate: [],
        AvgGrowth: []
      };
    }
    res[item.ReportTime].Rate.push(item.Rate);
    res[item.ReportTime].AvgGrowth.push(item.AvgGrowth);
  });
  return Object.values(res);
};

var data = [
  {
    ReportTime: "30 Apr 2017BDT",
    Rate: "1.00000",
    AvgGrowth: "0.0"
  },
  {
    ReportTime: "30 Apr 2017BDT",
    Rate: "0.01107",
    AvgGrowth: "0.1"
  },
  {
    ReportTime: "29 Apr 2017BDT",
    Rate: "1.00000",
    AvgGrowth: "0.0"
  },
  {
    ReportTime: "29 Apr 2017BDT",
    Rate: "0.01107",
    AvgGrowth: "-0.5"
  }
];

console.log(update(data));

​