根据多个过滤器JavaScript从JSON数据计算平均值
假设我们有一个像这样的对象数组-
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 }
];我们需要编写一个包含一个这样的数组的JavaScript函数。
该函数应执行以下操作-
将重复的供应商分组为一个唯一的单独对象（通过重复，我们指的是具有相同“SupplierName”和“Category”字段的对象）。
将他们的观点加在一起
向每个对象添加一个新的“平均”字段，其中包含该供应商的平均分数。
因此，最终输出应如下所示：
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;
//将“平均”属性作为项目计数器（在第一阶段）
};
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));输出结果
控制台中的输出将是-
[
{
"SupplierName": "John",
"Category ": "A",
"Points": 22,
"Average": 6
},
{
"SupplierName": "Praveen",
"Category ": "A",
"Points": 10,
"Average": 5
}
]