将对象数组({a:a，b:b，c:c}，{a:a，d:d，c:c})组合为({a:a，b:c，d:c}) [英] Combining object arrays ({a:a,b:b, c:c},{a:a,d:d,c:c}) to ({a:a,b:c,d:c})

问题描述

我有一个要获取的数据列表，我需要将其转换并透视"以将一列变成多列.

I have a list of data that I'm getting that I need to convert and "pivot" to turn one column into multiple columns.

我拥有的对象列表如下:

The list of objects I have looks like this:

var list = [
{
    "date": "2016-05-31",
    "action": "test",
    "value": 10
},
{
    "date": "2016-05-31",
    "action": "run",
    "value": 8
},
{
    "date": "2016-06-01",
    "action": "delete",
    "value" : 2
},
{
    "date": "2016-06-01",
    "action": "test",
    "value": 5
},
]

我需要将其转换为图表库，使其看起来像这样:

I need to convert this for a charting library so that it looks like this:

var list = [
{
    "date": "2016-05-31",
    "test": 10,
    "run": 8,
    "delete": 0
},
{
    "date": "2016-06-01",
    "test": 5,
    "run": 0,
    "delete": 2
}
]

是否有使用_.groupBy和_.map等underscore.js函数的简便方法?

Is there a fairly easy way to do this using underscore.js functions like _.groupBy and _.map etc...?

推荐答案

这是ES6解决方案，它不会对test，run或delete进行硬编码，但首先会检索数据中所有可能的操作:

Here is an ES6 solution, which does not hard-code test, run or delete, but first retrieves all possible actions in the data:

function pivot(list) {
    var actions = list.reduce( (actions, o) => (actions[o.action] = 0, actions), {} );
    var res = list.reduce( (res, o) => ((res[o.date] = res[o.date] || Object.assign({ date: o.date }, actions))[o.action] += o.value, res), {});
    return Object.keys(res).map(key => res[key]);
}

// Sample data
var list = [{
    "date": "2016-05-31",
    "action": "test",
    "value": 10
}, {
    "date": "2016-05-31",
    "action": "run",
    "value": 8
}, {
    "date": "2016-06-01",
    "action": "delete",
    "value": 2
}, {
    "date": "2016-06-01",
    "action": "test",
    "value": 5
}];
// Call
var res = pivot(list);
// Output
console.log(res);

如果在同一日期重复一个动作值，则将相应的值相加(假定为数值).

If an action value is repeated for the same date the corresponding values are added together (so numerical values are assumed).

在对速度的评论之后，我在这里介绍一个函数，该函数可以在一个循环中完成这项工作:

Following the comments on speed, I present here a function that does the job in one loop:

var list = [{
    "date": "2016-05-31",
    "action": "test",
    "value": 10
}, {
    "date": "2016-05-31",
    "action": "run",
    "value": 8
}, {
    "date": "2016-06-01",
    "action": "delete",
    "value": 2
}, {
    "date": "2016-06-01",
    "action": "test",
    "value": 5
}];

function pivot(list) {
    var res = {}, arr = [];
    for (var o of list)
        (res[o.date] || (arr[arr.push(res[o.date] = {
            date: o.date,
            test: 0,
            run : 0,
            "delete": 0
        })-1]))[o.action] += o.value;
    return arr;
}

var res = pivot(list);
console.log(res);

我已将其添加到测试服 Ismail RBOUH中创建.

I have added this to the test suit Ismail RBOUH created.

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