按嵌套鍵按對象數組分組

Question

我有以下數據：

const data = [
    {
        parent: {
            id: "1",
            name: "Europe"
        },
        item: {
            name: "Italy"
        },
        score: 5
    },
    {
        parent: {
            id: "1",
            name: "Europe"
        },
        item: {
            name: "France"
        },
        score: 4.5
    },
    {
        parent: {
            id: "1",
            name: "Europe"
        },
        item: {
            name: "UK"
        },
        score: 4.9
    },
    {
        parent: {
            id: "2",
            name: "Afrique"
        },
        item: {
            name: "Morocco"
        },
        score: 3.1
    },
    {
        parent: {
            id: "2",
            name: "Afrique"
        },
        item: {
            name: "Egypt"
        },
        score: 3.9
    }
];

我想根據parent.id對其進行parent.id並計算平均分數，因此我可以得到以下結果：

[
    {
        parent: {
            id: "1",
            name: "Europe",
            items: [
                {
                    name: "Italy"
                },
                {
                    name: "France"
                },
                {
                    name: "UK"
                }
            ],
            score: 4.8
        }
    },
    {
        parent: {
            id: "2",
            name: "Afrique",
            items: [
                {
                    name: "Morocco"
                },
                {
                    name: "Egypt"
                }
            ],
            score: 3.5
        }
    }
]

我使用了以下函數，但它不適用於嵌套鍵，而且它也不會返回所需的結果模式。

let group = cars.reduce((r, a) => {
   console.log("a", a);
   console.log('r', r);
   r[a.make] = [...r[a.parent.id] || [], a];
   return r;
}, {});
console.log("group", group);

Answer 1

您可以使用_reduce()函數： https : //developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduce

var result = data.reduce((res, data) => {
  if(!res[data.parent.id]) {
    data.item = [data.item];
    res[data.parent.id] = data;
  } else {
    res[data.parent.id]['item'].push(data['item']);
    res[data.parent.id]['score'] = (res[data.parent.id]['score'] + data['score'])/2;
  }
  return res;
}, [])
.filter(x => x != null)

 const data = [ { parent: { id: "1", name: "Europe" }, item: { name: "Italy" }, score: 5 }, { parent: { id: "1", name: "Europe" }, item: { name: "France" }, score: 4.5 }, { parent: { id: "1", name: "Europe" }, item: { name: "UK" }, score: 4.9 }, { parent: { id: "2", name: "Afrique" }, item: { name: "Morocco" }, score: 3.1 }, { parent: { id: "2", name: "Afrique" }, item: { name: "Egypt" }, score: 3.9 } ]; var result = data.reduce((res, data) => { if(!res[data.parent.id]) { data.item = [data.item]; res[data.parent.id] = data; } else { res[data.parent.id]['item'].push(data['item']); res[data.parent.id]['score'] = (res[data.parent.id]['score'] + data['score'])/2; } return res; }, []) .filter(x => x != null) console.log(result)

Answer 2

創建一個對象/哈希圖，然后將結果對象格式化為一個數組。

let continents = {}
data.forEach(function(country){
    const continent_id = country.parent.id
    let continent = continents[continent_id]
    if(!continent){
        continent = {
             id: continent_id,
             name: country.parent.name,
             items: [],
        }
        continents[continent_id] = continent
    }
    continent.items.push({
       name: country.item.name,
       score: country.score
    })

})
continents = Object.entries(continents).map(item => ({parent: item[1]}))
console.log(continents)

輸出：

[
    {
        "parent":{
            "id":"1",
            "name":"Europe",
            "items":[
                {
                    "name":"Italy",
                    "score":5
                },
                {
                    "name":"France",
                    "score":4.5
                },
                {
                    "name":"UK",
                    "score":4.9
                }
            ]
        }
    },
    {
        "parent":{
            "id":"2",
            "name":"Afrique",
            "items":[
                {
                    "name":"Morocco",
                    "score":3.1
                },
                {
                    "name":"Egypt",
                    "score":3.9
                }
            ]
        }
    }
]

Answer 3

根據您提供的數據，如果您還需要計算score屬性的平均值，請使用以下 reduce 方法：它將遍歷您的數據，對其進行分組並計算總分值和分值計數。 在減少組對象執行映射后，將使用totalScore和scoreCount計算所有組的totalScore scoreCount

 const data = [ { parent: { id: "1", name: "Europe" }, item: { name: "Italy" }, score: 5 }, { parent: { id: "1", name: "Europe" }, item: { name: "France" }, score: 4.5 }, { parent: { id: "1", name: "Europe" }, item: { name: "UK" }, score: 4.9 }, { parent: { id: "2", name: "Afrique" }, item: { name: "Morocco" }, score: 3.1 }, { parent: { id: "2", name: "Afrique" }, item: { name: "Egypt" }, score: 3.9 } ]; let group = data.reduce((acc, rec) => { if (acc.find(item => item.parent.id === rec.parent.id)) { const idx = acc.findIndex(item => item.parent.id === rec.parent.id) acc[idx].parent.items = acc[idx].parent.items.concat(rec.item) acc[idx].parent.score += rec.score acc[idx].parent.scoreCount +=1 } else { acc = acc.concat({parent: {...rec.parent, score: rec.score, items: [rec.item], scoreCount:1}}) } return acc }, []).map(it => ({parent: {id: it.parent.id, name:it.parent.name, score: (it.parent.score / it.parent.scoreCount), items: it.parent.items}})); console.log("group", group);