如何按键对对象数组进行分组 [英] How to group an array of objects by key

问题描述

有没有人知道（如果可能的话，还是lodash）通过对象键对对象数组进行分组，然后根据分组创建一个新的对象数组？例如，我有一系列汽车对象：

Does anyone know of a (lodash if possible too) way to group an array of objects by an object key then create a new array of objects based on the grouping? For example, I have an array of car objects:

var cars = [
    {
        'make': 'audi',
        'model': 'r8',
        'year': '2012'
    }, {
        'make': 'audi',
        'model': 'rs5',
        'year': '2013'
    }, {
        'make': 'ford',
        'model': 'mustang',
        'year': '2012'
    }, {
        'make': 'ford',
        'model': 'fusion',
        'year': '2015'
    }, {
        'make': 'kia',
        'model': 'optima',
        'year': '2012'
    },
];

我想制作一个新的汽车对象数组，按 make <分组/ code>：

I want to make a new array of car objects that's grouped by make:

var cars = {
    'audi': [
        {
            'model': 'r8',
            'year': '2012'
        }, {
            'model': 'rs5',
            'year': '2013'
        },
    ],

    'ford': [
        {
            'model': 'mustang',
            'year': '2012'
        }, {
            'model': 'fusion',
            'year': '2015'
        }
    ],

    'kia': [
        {
            'model': 'optima',
            'year': '2012'
        }
    ]
}

推荐答案

Timo的答案是我如何做到的。简单 _。groupBy ，并允许在分组结构中的对象中进行一些复制。

Timo's answer is how I would do it. Simple _.groupBy, and allow some duplications in the objects in the grouped structure.

然而，OP还要求删除重复的 make 键。如果你想一路走下去：

However the OP also asked for the duplicate make keys to be removed. If you wanted to go all the way:

var grouped = _.mapValues(_.groupBy(cars, 'make'),
                          clist => clist.map(car => _.omit(car, 'make')));

console.log(grouped);

收益率：

{ audi:
   [ { model: 'r8', year: '2012' },
     { model: 'rs5', year: '2013' } ],
  ford:
   [ { model: 'mustang', year: '2012' },
     { model: 'fusion', year: '2015' } ],
  kia: [ { model: 'optima', year: '2012' } ] }

如果您想使用Underscore执行此操作。 js，请注意其 _。mapValues 的版本称为 _。mapObject 。

If you wanted to do this using Underscore.js, note that its version of _.mapValues is called _.mapObject.

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