Group By、Count Distinct、JavaScript数组中对象的总计
Group By、Count Distinct、JavaScript数组中对象的总计
提问于 2018-08-23 00:31:38
这可能是一种补救措施，但我想不通。我尝试过使用d3并尝试使用lodash来获得一个有效的解决方案，但没有得到任何接近的结果。
我在JavaScript中有一个对象数组。如果选择的值为true，我想创建一个按版本名称分组的对象，其中包含不同区域的计数，以及每个版本的总数。例如使用对象...
[
{ Selcted: false, Version Name: "aaa", Zone: "11111", Value: 5 },
{ Selcted: false, Version Name: "aaa", Zone: "11111", Value: 10 },
{ Selcted: true, Version Name: "aaa", Zone: "11111", Value: 15 },
{ Selcted: true, Version Name: "aaa", Zone: "11111", Value: 20 },
{ Selcted: true, Version Name: "aaa", Zone: "22222", Value: 25 },
{ Selcted: true, Version Name: "bbb", Zone: "22222", Value: 30 },
{ Selcted: true, Version Name: "bbb", Zone: "22222", Value: 35 },
{ Selcted: true, Version Name: "bbb", Zone: "2222", Value: 40 }
]应该返回一个结果
[
{ Version Name: "aaa", Zone Count: "2", Value Sum: 50 },
{ Version Name: "bbb", Zone Count: "1", Value Sum: 105 },
]回答 8
Stack Overflow用户
回答已采纳
发布于 2018-08-23 00:45:07
这使用了我最喜欢的groupBy函数:)一旦你得到了组，你做另一个组来获得区域计数，并进行一次reduce来得到你的总和。
简而言之
const byName = groupBy(input.filter(it => it.Selcted), it => it['Version Name'])
const output = Object.keys(byName).map(name => {
const byZone = groupBy(byName[name], it => it.Zone)
const sum = byName[name].reduce((acc, it) => acc + it.Value, 0)
return {
'Version Name': name,
ZoneCount: Object.keys(byZone).length,
ValueSum: sum
}
})别忘了，你需要用引号将“版本名”作为键使用。
下面是您的数据集的一个工作示例。
function groupBy(a, keyFunction) {
const groups = {};
a.forEach(function(el) {
const key = keyFunction(el);
if (key in groups === false) {
groups[key] = [];
}
groups[key].push(el);
});
return groups;
}
const input = [{
Selcted: false,
'Version Name': "aaa",
Zone: "11111",
Value: 5
},
{
Selcted: false,
'Version Name': "aaa",
Zone: "11111",
Value: 10
},
{
Selcted: true,
'Version Name': "aaa",
Zone: "11111",
Value: 15
},
{
Selcted: true,
'Version Name': "aaa",
Zone: "11111",
Value: 20
},
{
Selcted: true,
'Version Name': "aaa",
Zone: "22222",
Value: 25
},
{
Selcted: true,
'Version Name': "bbb",
Zone: "22222",
Value: 30
},
{
Selcted: true,
'Version Name': "bbb",
Zone: "22222",
Value: 35
},
{
Selcted: true,
'Version Name': "bbb",
Zone: "2222",
Value: 40
}
]
const byName = groupBy(input.filter(it => it.Selcted), it => it['Version Name'])
const output = Object.keys(byName).map(name => {
const byZone = groupBy(byName[name], it => it.Zone)
const sum = byName[name].reduce((acc, it) => acc + it.Value, 0)
return {
'Version Name': name,
ZoneCount: Object.keys(byZone).length,
ValueSum: sum
}
})
console.log(output)
Stack Overflow用户
发布于 2018-08-23 00:46:14
使用filter获取所需的项目后，您可以通过两个步骤完成此操作，即先使用reduce，然后使用map
let input = [
{ Selcted: false, "Version Name": "aaa", Zone: "11111", Value: 5 },
{ Selcted: false, "Version Name": "aaa", Zone: "11111", Value: 10 },
{ Selcted: true, "Version Name": "aaa", Zone: "11111", Value: 15 },
{ Selcted: true, "Version Name": "aaa", Zone: "11111", Value: 20 },
{ Selcted: true, "Version Name": "aaa", Zone: "22222", Value: 25 },
{ Selcted: true, "Version Name": "bbb", Zone: "22222", Value: 30 },
{ Selcted: true, "Version Name": "bbb", Zone: "22222", Value: 35 },
{ Selcted: true, "Version Name": "bbb", Zone: "2222", Value: 40 }
]
var result = input.filter(x => x.Selcted)
.reduce( (acc, curr) => {
let item = acc.find(x => x.version == curr["Version Name"]);
if(!item){
item = {version: curr["Version Name"], zones:{}}
acc.push(item);
}
item.zones[curr.Zone] = (item.zones[curr.Zone] || 0) + curr.Value
return acc;
},[])
.map(x => ({
"Version Name": x.version,
"Zone Count": Object.keys(x.zones).length,
"Value Sum": Object.values(x.zones).reduce( (a,b) => a+b ,0)
}))
console.log(result);
Stack Overflow用户
发布于 2018-08-23 01:08:47
首先过滤掉，然后分组，然后计算区域，为此我们需要在数组上使用一些heler函数：
Array.prototype.groupBy = function groupBy(key) {
const hash = {}, result = [];
for(const el of this) {
if(hash[ el[key] ]) {
hash[ el[key] ].push(el);
} else {
result.push({
key: el[key],
values: hash[ el[key] ] = [ el ],
});
}
}
return result;
};
Array.prototype.key = function(key) {
return this.map(el => el[key]);
};
Array.prototype.sum = function(key) {
return this.reduce((total, el) => total + (key ? el[key] : el), 0);
};
Array.prototype.unique = function() {
return [...new Set(this)];
};这实际上是相当多的代码，但现在我们可以使用它来构建我们的结果：
const result = array
.filter(el => el.Selected)
.groupBy("Version Name")
.map(({ key, values }) => ({
"Version Name": key,
"Value Sum": values.sum("Sum"),
"Zone Count":values.key("Zone").unique().length,
}));页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/51971373
复制相关文章
相似问题
腾讯云开发者
