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'
}
]
}
我用REAL GROUP BY作为JS数组的例子和这个任务完全一样
const inputArray = [
{ Phase: "Phase 1", Step: "Step 1", Task: "Task 1", Value: "5" },
{ Phase: "Phase 1", Step: "Step 1", Task: "Task 2", Value: "10" },
{ Phase: "Phase 1", Step: "Step 2", Task: "Task 1", Value: "15" },
{ Phase: "Phase 1", Step: "Step 2", Task: "Task 2", Value: "20" },
{ Phase: "Phase 2", Step: "Step 1", Task: "Task 1", Value: "25" },
{ Phase: "Phase 2", Step: "Step 1", Task: "Task 2", Value: "30" },
{ Phase: "Phase 2", Step: "Step 2", Task: "Task 1", Value: "35" },
{ Phase: "Phase 2", Step: "Step 2", Task: "Task 2", Value: "40" }
];
var outObject = inputArray.reduce(function(a, e) {
// GROUP BY estimated key (estKey), well, may be a just plain key
// a -- Accumulator result object
// e -- sequentally checked Element, the Element that is tested just at this itaration
// new grouping name may be calculated, but must be based on real value of real field
let estKey = (e['Phase']);
(a[estKey] ? a[estKey] : (a[estKey] = null || [])).push(e);
return a;
}, {});
console.log(outObject);
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);
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。
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);
.as-console-wrapper { max-height: 100% !important; top: 0; }
<script src='https://cdn.jsdelivr.net/g/lodash@4(lodash.min.js+lodash.fp.min.js)'></script>
Var汽车= [{
:“奥迪”,
模型:“r8”,
:“2012”
},{
:“奥迪”,
模型:“生活费”,
:“2013”
},{
:“福特”,
模型:“野马”,
:“2012”
},{
:“福特”,
模型:“融合”,
:“2015”
},{
:“克钦独立军”,
模型:“最佳状态”,
:“2012”
})。Reduce ((r, car) => {
const {
模型中,
一年,
使
} =汽车;
R [make] =[…]R [make] || []， {
模型中,
一年
});
返回r;
}, {});
console.log(汽车);
