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?
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)
//}
为了补充Scott Sauyet的答案,一些人在评论中询问如何使用他的函数按值1、值2等分组,而不是仅对一个值分组。
只需编辑他的求和函数:
DataGrouper.register("sum", function(item) {
return _.extend({}, item.key,
{VALUE1: _.reduce(item.vals, function(memo, node) {
return memo + Number(node.VALUE1);}, 0)},
{VALUE2: _.reduce(item.vals, function(memo, node) {
return memo + Number(node.VALUE2);}, 0)}
);
});
保持主组(DataGrouper)不变:
var DataGrouper = (function() {
var has = function(obj, target) {
return _.any(obj, function(value) {
return _.isEqual(value, target);
});
};
var keys = function(data, names) {
return _.reduce(data, function(memo, item) {
var key = _.pick(item, names);
if (!has(memo, key)) {
memo.push(key);
}
return memo;
}, []);
};
var group = function(data, names) {
var stems = keys(data, names);
return _.map(stems, function(stem) {
return {
key: stem,
vals:_.map(_.where(data, stem), function(item) {
return _.omit(item, names);
})
};
});
};
group.register = function(name, converter) {
return group[name] = function(data, names) {
return _.map(group(data, names), converter);
};
};
return group;
}());