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，也可以使用 lodash)通过对象键对对象数组进行分组，然后根据分组创建新的对象数组的方法吗?例如，我有一个汽车对象数组:

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'
    },
];

我想创建一个由 make 分组的新汽车对象数组:

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 的回答 是我会怎么做.简单的_.groupBy，并允许在分组结构中的对象中有一些重复.

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);

产量:

{ 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.js 执行此操作，请注意它的 _.mapValues 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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