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'
}
]
}
只需简单的forEach循环就可以在这里工作，不需要任何库
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'
},
];
let ObjMap ={};
cars.forEach(element => {
var makeKey = element.make;
if(!ObjMap[makeKey]) {
ObjMap[makeKey] = [];
}
ObjMap[makeKey].push({
model: element.model,
year: element.year
});
});
console.log(ObjMap);
@metakungfu answer略有不同，主要区别在于它从结果对象中省略了原始键，因为在某些情况下对象本身不再需要它，因为它现在在父对象中可用。
const groupBy = (_k, a) => a.reduce((r, {[_k]:k, ...p}) => ({
...r, ...{[k]: (
r[k] ? [...r[k], {...p}] : [{...p}]
)}
}), {});
考虑到您的原始输入对象:
console.log(groupBy('make', cars));
会导致:
{
audi: [
{ model: 'r8', year: '2012' },
{ model: 'rs5', year: '2013' }
],
ford: [
{ model: 'mustang', year: '2012' },
{ model: 'fusion', year: '2015' }
],
kia: [
{ model: 'optima', year: '2012' }
]
}
另一个解决方案:
Var汽车= [
{“使”:“奥迪”,“模型”:“r8”,“年”:“2012”},{“使”:“奥迪”,“模型”:“生活费”,“年”:“2013”},
{“使”:“福特”,“模型”:“野马”,“年”:“2012”},{“使”:“福特”,“模型”:“融合”,“年”:“2015”},
{'make': 'kia'，'model': 'optima'，'year': '2012'}，
];
const reducedCars =汽车。Reduce ((acc， {make, model, year}) => (
｛
acc,
[make]: acc[make] ?[…Acc [make]， {model, year}]: [{model, year}]，
｝
), {});
console.log (reducedCars);
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);
使用lodash/fp，你可以使用_.flow()创建一个函数，它首先按键分组，然后映射每个组，并从每个项中省略一个键:
const { flow, groupBy, mapValues, map, omit } = _;
const groupAndOmitBy = key => flow(
groupBy(key),
mapValues(map(omit(key)))
);
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' }];
const groupAndOmitMake = groupAndOmitBy('make');
const result = groupAndOmitMake(cars);
console.log(result);
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