有人知道一种方法(lodash如果可能的话)通过对象键分组对象数组,然后根据分组创建一个新的对象数组吗?例如,我有一个汽车对象数组:
const 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'
},
];
我想创建一个新的汽车对象数组,由make分组:
const cars = {
'audi': [
{
'model': 'r8',
'year': '2012'
}, {
'model': 'rs5',
'year': '2013'
},
],
'ford': [
{
'model': 'mustang',
'year': '2012'
}, {
'model': 'fusion',
'year': '2015'
}
],
'kia': [
{
'model': 'optima',
'year': '2012'
}
]
}
提莫的答案是我会怎么做。简单的_。groupBy,并允许在分组结构中的对象中有一些重复。
然而,OP还要求删除重复的make键。如果你想从头到尾:
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' } ]
}
如果你想使用Underscore.js来实现这个功能,请注意它的_. js版本。mapValues被称为_.mapObject。
创建一个可以重用的方法
Array.prototype.groupBy = function(prop) {
return this.reduce(function(groups, item) {
const val = item[prop]
groups[val] = groups[val] || []
groups[val].push(item)
return groups
}, {})
};
下面你可以根据任何标准进行分组
const groupByMake = cars.groupBy('make');
console.log(groupByMake);
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'
},
];
//re-usable method
Array.prototype.groupBy = function(prop) {
return this.reduce(function(groups, item) {
const val = item[prop]
groups[val] = groups[val] || []
groups[val].push(item)
return groups
}, {})
};
// initiate your groupBy. Notice the recordset Cars and the field Make....
const groupByMake = cars.groupBy('make');
console.log(groupByMake);
//At this point we have objects. You can use Object.keys to return an array
你也可以像这样使用数组#forEach()方法:
const 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' }];
let newcars = {}
cars.forEach(car => {
newcars[car.make] ? // check if that array exists or not in newcars object
newcars[car.make].push({model: car.model, year: car.year}) // just push
: (newcars[car.make] = [], newcars[car.make].push({model: car.model, year: car.year})) // create a new array and push
})
console.log(newcars);