[removed] Transform array of object response via l

问题:

I am working with highChart to create a column chart. Any how I reached to creating following arrayofObj via communicating with database.

Now, I require to transform following source array of object to below output.

var source = [
{data: 258, name: '2014'}
{data: 18, name: '2016'}
{data: 516, name: '2014'}
{data: 0, name: '2014'}
{data: 354, name: '2014'}
{data: 18, name: '2016'}
]`

Convert this array of object to

Output

[{
    name: '2014',
    data: [258, 516, 354]
  }, {
    name: '2016',
    data: [18, 0, 18]
}]

Basically, I want my array to group by name (year) and data should be in array

Here is the solutions which i have applied.

var source = [];
_.each(source, function(singlerec) {
      source.push({
        name: singlerec.name,
        data: singlerec.data  // Here It only assign single record
      });
    });

回答1:

In Lodash, I always use _.groupBy and then _.map to the output format.

var source = [{"data":258,"name":"2014"},{"data":18,"name":"2016"},{"data":516,"name":"2014"},{"data":0,"name":"2014"},{"data":354,"name":"2014"},{"data":18,"name":"2016"}];

var output = _(source)
  .groupBy('name')
  .map(function(v, k) { return { name: k, data: _.map(v, 'data') } })
  .value();

console.log(output);

<script src="https://cdn.jsdelivr.net/lodash/4.13.1/lodash.min.js"></script>

回答2:

I use a pure javascript function:

const pick = (obj, paths) => ({...paths.reduce((a, k) => ({...a, [k]: obj[k]}), {})})

function groupByAndConcat(data, groupBy, sums) {
    return data.reduce((results, r) => {
        const e = results.find((x) => groupBy.every((g) => x[g] === r[g]));
        if (e) {
            sums.forEach((k) => e[k] = [].concat(e[k], r[k]));
        } else {
            results.push(pick(r, groupBy.concat(sums)));
        }
        return results;
    }, []);
}

So given your sample source:

const source = [
    {data: 258, name: '2014'},
    {data: 18, name: '2016'},
    {data: 516, name: '2014'},
    {data: 0, name: '2014'},
    {data: 354, name: '2014'},
    {data: 18, name: '2016'},
];

console.log(groupByAndConcat(source, ["name"], ["data"]))

outputs:

[{ name: "2014", data: Array [258, 516, 0, 354] }, { name: "2016", data: Array [18, 18] }]

It is also possible to group by or do operations on several props:

groupByAndConcat(source, ["name","month"], ["data","data2"])

回答3:

there's a way to iterate array once with reduce and even without lodash.

source.reduce((p, n) => {
    (p[n.name] || (p[n.name] = [])).push(n.data);
    return p
}, {})