按数组中的对象分组最有效的方法是什么?
例如,给定此对象数组:
[
{ 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" }
]
我正在表格中显示这些信息。我想通过不同的方法进行分组,但我想对值求和。
我将Undercore.js用于其groupby函数,这很有用,但并不能完成全部任务,因为我不希望它们“拆分”,而是“合并”,更像SQL groupby方法。
我要找的是能够合计特定值(如果需要)。
因此,如果我按阶段分组,我希望收到:
[
{ Phase: "Phase 1", Value: 50 },
{ Phase: "Phase 2", Value: 130 }
]
如果我组了阶段/步骤,我会收到:
[
{ Phase: "Phase 1", Step: "Step 1", Value: 15 },
{ Phase: "Phase 1", Step: "Step 2", Value: 35 },
{ Phase: "Phase 2", Step: "Step 1", Value: 55 },
{ Phase: "Phase 2", Step: "Step 2", Value: 75 }
]
是否有一个有用的脚本,或者我应该坚持使用Undercore.js,然后遍历生成的对象,自己计算总数?
此解决方案采用任意函数(而不是键),因此比上述解决方案更灵活,并允许箭头函数,这与LINQ中使用的lambda表达式类似:
Array.prototype.groupBy = function (funcProp) {
return this.reduce(function (acc, val) {
(acc[funcProp(val)] = acc[funcProp(val)] || []).push(val);
return acc;
}, {});
};
注意:是否要扩展Array的原型取决于您。
大多数浏览器支持的示例:
[{a:1,b:"b"},{a:1,c:"c"},{a:2,d:"d"}].groupBy(function(c){return c.a;})
使用箭头函数(ES6)的示例:
[{a:1,b:"b"},{a:1,c:"c"},{a:2,d:"d"}].groupBy(c=>c.a)
以上两个示例都返回:
{
"1": [{"a": 1, "b": "b"}, {"a": 1, "c": "c"}],
"2": [{"a": 2, "d": "d"}]
}
我已经改进了答案。此函数获取组字段数组并返回分组对象,该对象的键也是组字段的对象。
function(xs, groupFields) {
groupFields = [].concat(groupFields);
return xs.reduce(function(rv, x) {
let groupKey = groupFields.reduce((keyObject, field) => {
keyObject[field] = x[field];
return keyObject;
}, {});
(rv[JSON.stringify(groupKey)] = rv[JSON.stringify(groupKey)] || []).push(x);
return rv;
}, {});
}
let x = [
{
"id":1,
"multimedia":false,
"language":["tr"]
},
{
"id":2,
"multimedia":false,
"language":["fr"]
},
{
"id":3,
"multimedia":true,
"language":["tr"]
},
{
"id":4,
"multimedia":false,
"language":[]
},
{
"id":5,
"multimedia":false,
"language":["tr"]
},
{
"id":6,
"multimedia":false,
"language":["tr"]
},
{
"id":7,
"multimedia":false,
"language":["tr","fr"]
}
]
groupBy(x, ['multimedia','language'])
//{
//{"multimedia":false,"language":["tr"]}: Array(3),
//{"multimedia":false,"language":["fr"]}: Array(1),
//{"multimedia":true,"language":["tr"]}: Array(1),
//{"multimedia":false,"language":[]}: Array(1),
//{"multimedia":false,"language":["tr","fr"]}: Array(1)
//}