当“旋转”时避免嵌套地图。多维数组 [英] Avoiding nesting maps when "pivoting" multidimensional array

问题描述

我的数据格式为

I have data in the format

[
  {
    "timeline_map": {
      "2017-05-06": 770,
      "2017-05-07": 760,
      "2017-05-08": 1250
         ...
    }
  },
  {
    "timeline_map": {
      "2017-05-06": 590,
      "2017-05-07": 210,
      "2017-05-08": 300
         ...
    }
  },
  {
    "timeline_map": {
      "2017-05-06": 890,
      "2017-05-07": 2200,
      "2017-05-08": 1032
         ...
    }
  }
]

为了在谷歌图表中使用我需要更改为格式

that in order to use in a google chart I need to change to the format

[
  ["2017-05-06", 770, 590, 890, ...],
  ["2017-05-07", 760, 210, 2200, ...],
  ["2017-05-08", 1250, 300, 1032, ...]
]

我写了以下内容来进行转换

I wrote the following to make the transformation

let mapped = _.map(
  chartData.results[0].timeline_map, (timestampVal, timestampKey) => (
  [timestampKey].concat(
    _.map(
      chartData.results, lineData => (
        lineData.timeline_map[timestampKey]
        )
      )
    )
  )
)

这有效，但我在考虑嵌套 map s不是一个好主意，因为它将如何增加被映射数组长度的平方的循环量。有没有更好的方法来达到预期的结果。

This works, but I'm thinking that nesting the maps is not a good idea because how it will increase the amount of looping by the square off the length of the array being mapped. Is there a better way to achieve the desired result here.

JSBIN

推荐答案

您可以在散列表上使用闭包，日期键。

You could use a closure over a hash table and assign the values accordingly to the date keys.

var data = [{ timeline_map: { "2017-05-06": 770, "2017-05-07": 760, "2017-05-08": 1250 } }, { timeline_map: { "2017-05-06": 590, "2017-05-07": 210, "2017-05-08": 300 } }, { timeline_map: { "2017-05-06": 890, "2017-05-07": 2200, "2017-05-08": 1032 } }],
    grouped = data.reduce(function (hash) {
        return function (r, o) {
            Object.keys(o.timeline_map).forEach(function (k) {
                if (!hash[k]) {
                    hash[k] = [k];
                    r.push(hash[k]);
                }
                hash[k].push(o.timeline_map[k]);
            });
            return r;
        };
    }(Object.create(null)), []);

console.log(grouped);

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

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