将对象数组映射到具有数组的分组对象

debugcn 发表于 Dev

ptrugby4141

我认为我的问题很简单，我似乎无法弄清楚。我需要从一组对象中取出：

    let testArrays = [
{ "containerType": "2 Gallon", "wasteType": "10000001", "vol": "2 Gallons" },
{ "containerType": "2 Gallon", "wasteType": "10000001", "vol": "2 Gallons" },
{ "containerType": "2 Gallon", "wasteType": "10000002", "vol": "2 Gallons" },
{ "containerType": "2 Gallon", "wasteType": "10000002", "vol": "2 Gallons" },
{ "containerType": "2 Gallon", "wasteType": "10000003", "vol": "2 Gallons" },
{ "containerType": "5 Gallon", "wasteType": "10000003", "vol": "5 Gallons" },
{ "containerType": "5 Gallon", "wasteType": "10000003", "vol": "5 Gallons" },
{ "containerType": "5 Gallon", "wasteType": "10000003", "vol": "5 Gallons" },
{ "containerType": "5 Gallon", "wasteType": "10000004", "vol": "5 Gallons" }
]

对于内部带有数组的分组对象，按上面的“wasteType”分组并带有计数。体积将通过将计数乘以“vol”中的值来创建，我可以使用 parsefloat 我相信：

    let wastes = {
        "10000001": [
            {
                "containerType": "2 Gallon",
                "count": 2,
                "vol": "4 Gallons"
            }
        ],
        "10000002": [
            {
                "containerType": "2 Gallon",
                "count": 2,
                "vol": "4 Gallons"
            }
        ],
        "10000003": [
            {
                "containerType": "1 Gallon",
                "count": 1,
                "vol": "2 Gallons"
            },
            {
                "containerType": "5 Gallon",
                "count": 3,
                "vol": "15 Gallons"
            }
        ],
        "10000004": [
            {
                "containerType": "5 Gallon",
                "count": 1,
                "vol": "5 Gallons"
            }
        ],
    }

我知道我应该为此使用 array.map() 但我不知道该怎么做。我到处都在寻找这个特定的例子，但找不到。非常感谢所有帮助。

代码狂人

你需要使用reduce而不是map

循环使用数组wasteType作为属性名称
如果属性已经不在输出对象上，则使用当前元素值初始化
将计数增加 1
final再次循环以获得 vol，即count * vol

let testArrays = [{"containerType": "2 Gallon","wasteType": "10000001","vol": "2 Gallons"}, {"containerType": "2 Gallon","wasteType": "10000001","vol": "2 Gallons"}, {"containerType": "2 Gallon","wasteType": "10000002","vol": "2 Gallons"}, {"containerType": "2 Gallon","wasteType": "10000002","vol": "2 Gallons"}, {"containerType": "2 Gallon","wasteType": "10000003","vol": "2 Gallons"}, {"containerType": "5 Gallon","wasteType": "10000003","vol": "5 Gallons"}, {  "containerType": "5 Gallon","wasteType": "10000003","vol": "5 Gallons"}, {"containerType": "5 Gallon","wasteType": "10000003","vol": "5 Gallons"}, {"containerType": "5 Gallon","wasteType": "10000004","vol": "5 Gallons"}]

let final = testArrays.reduce((op, { containerType, wasteType,vol}) => {
  let obj = { containerType, vol, count: 0 }
  op[wasteType] = op[wasteType] || new Map([[containerType,obj]])
  if(op[wasteType].has(containerType)){
    op[wasteType].get(containerType).count++
  } else{
    obj.count++
    op[wasteType].set(containerType, obj)
  }
  return op
}, {})

for(let key in final){
  final[key] = [...final[key].values()].map(value=>{
  let { containerType, vol, count} = value
  let finalVol = (vol.replace(/[.\D+]/g, '') * count) + " Gallons"
   return { containerType, vol:finalVol, count }
  })
}

console.log(final)

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