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法律研究根據多個篩選條件從 JSON 資料中計算平均值 JavaScript
假設我們有一個這樣的物件陣列 −
const arr = [
{ "SupplierName" : "John", "Category " : "A", "Points" : 3 },
{ "SupplierName" : "John", "Category " : "A", "Points" : 11 },
{ "SupplierName" : "John", "Category " : "A", "Points" : undefined },
{ "SupplierName" : "John", "Category " : "B", "Points" : 2 },
{ "SupplierName" : "John", "Category " : "B", "Points" : 6 },
{ "SupplierName" : "Praveen", "Category " : "A", "Points" : 3 },
{ "SupplierName" : "Praveen", "Category " : "A", "Points" : 7 }
];我們需要編寫一個接收此類陣列的 JavaScript 函式。
該函式應執行以下操作 −
- 將重複的供應商分組到一個唯一獨立的物件中（重複指的是“SupplierName”和“Category”欄位相同的物件）。
- 將它們的積分加在一起
- 向每個物件新增一個新的“平均值”欄位，其中包含該供應商的平均積分。
因此，最終輸出應如下所示 −
const output = [
{ "SupplierName" : "John", "Category " : "A", "Points" : 14, "Average" : 7 },
{ "SupplierName" : "John", "Category " : "B", "Points" : 8, "Average" : 4 },
{ "SupplierName" : "Praveen", "Category " : "A", "Points" : 10, "Average" : 5 }
];示例
const arr = [
{ "SupplierName" : "John", "Category " : "A", "Points" : 3 },
{ "SupplierName" : "John", "Category " : "A", "Points" : 11 },
{ "SupplierName" : "John", "Category " : "A", "Points" : undefined },
{ "SupplierName" : "John", "Category " : "B", "Points" : 2 },
{ "SupplierName" : "John", "Category " : "B", "Points" : 6 },
{ "SupplierName" : "Praveen", "Category " : "A", "Points" : 3 },
{ "SupplierName" : "Praveen", "Category " : "A", "Points" : 7 }
];
const groupAndAverage = (arr = []) => {
const groups = arr.reduce((acc, obj) => {
const name = obj.SupplierName + obj.Category;
if (acc[name]) {
if (obj.Points) (acc[name].Points += obj.Points) && ++acc[name].Average;
}
else { acc[name] = obj;
acc[name].Average = 1;
// taking 'Average' attribute as an items counter(on the first phase)
};
return acc;
}, {});
// getting "average of Points" const res = Object.keys(groups).map( name => { groups[name].Average = Math.round(groups[name].Points/groups[name].Average);
return groups[name];
});
return res;
}; console.log(JSON.stringify(groupAndAverage(arr), undefined, 4));輸出
並且控制檯中的輸出將為 −
[
{
"SupplierName": "John",
"Category ": "A",
"Points": 22,
"Average": 6
},
{
"SupplierName": "Praveen",
"Category ": "A",
"Points": 10,
"Average": 5
}
]
更新於： 23-11-2020
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