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'
}
]
}
letfinaldata=[]
let data =[{id:1,name:"meet"},{id:2,name:"raj"},{id:1,name:"hari"},{id:3,name:"hari"},{id:2,name:"ram"}]
data = data.map((item)=>
{
return {...item,
name: [item.name]
}
}) // Converting the name key from string to array
let temp = [];
for(let i =0 ;i<data.length;i++)
{
const index = temp.indexOf(data[i].id) // Checking if the object id is already present
if(index>=0)
{
letfinaldata[index].name = [...letfinaldata[index].name,...data[i].name] // If present then append the name to the name of that object
}
else{
temp.push(data[i].id); // Push the checked object id
letfinaldata.push({...data[i]}) // Push the object
}
}
console.log(letfinaldata)
输出
[ { id: 1, name: [ 'meet', 'hari' ] },
{ id: 2, name: [ 'raj', 'ram' ] },
{ id: 3, name: [ 'hari' ] } ]
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);
@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' }
]
}
对于key可以为null的情况,我们希望将它们分组为其他
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'},
{'make':'kia','model':'optima','year':'2033'},
{'make':null,'model':'zen','year':'2012'},
{'make':null,'model':'blue','year':'2017'},
];
result = cars.reduce(function (r, a) {
key = a.make || 'others';
r[key] = r[key] || [];
r[key].push(a);
return r;
}, Object.create(null));
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。