lodash - 分组和填充数组

Question

使用 lodash，我如何将具有相同生日的人的姓名分组，如下所示？

我使用嵌套的 for 循环将其写出来，但我认为在 lodash 中会有更优雅的方式来执行此操作。我没有使用太多，并试图弄清楚要使用哪个功能。

[
    { "birthdate": "1993", "name": "Ben" },
    { "birthdate": "1994", "name": "John" },
    { "birthdate": "1995", "name": "Larry" },
    { "birthdate": "1995", "name": "Nicole" },
    { "birthdate": "1996", "name": "Jane" },
    { "birthdate": "1996", "name": "Janet" },
    { "birthdate": "1996", "name": "Dora" },
]

到

[
    { "birthdate": "1993", "names": [ "Ben" ] }, 
    { "birthdate": "1994", "names": [ "John"] },
    { "birthdate": "1995", "names": [ "Larry", "Nicole" ] }, 
    { "birthdate": "1996", "names": [ "Jane", "Janet", "Dora" ] }        
]

Answer 1

您可以使用groupBy() 将集合中的每个项目按birthdate 分组。将项目分组后，您可以使用map() 迭代每个组并将它们形成一个新格式，包括birthdate 和names。要从分组项中获取名称数组，可以再次使用map() 函数返回所有name 值。

var result = _(source)
    .groupBy('birthdate')
    .map(function(items, bdate) {
      return {
        birthdate: bdate,
        names: _.map(items, 'name')
      };
    }).value();

var source = [
    { "birthdate": "1993", "name": "Ben" },
    { "birthdate": "1994", "name": "John" },
    { "birthdate": "1995", "name": "Larry" },
    { "birthdate": "1995", "name": "Nicole" },
    { "birthdate": "1996", "name": "Jane" },
    { "birthdate": "1996", "name": "Janet" },
    { "birthdate": "1996", "name": "Dora" },
];
  
var result = _(source)
    .groupBy('birthdate')
    .map(function(items, bdate) {
      return {
        birthdate: bdate,
        names: _.map(items, 'name')
      };
    }).value();

document.body.innerHTML = '<pre>' + JSON.stringify(result, 0, 4) + '</pre>';

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.js"></script>

Answer 2

您可以使用reduce() 和find()

   let arr = [{
	"birthdate": "1993",
	"name": "Ben"
},
{
	"birthdate": "1994",
	"name": "John"
},
{
	"birthdate": "1995",
	"name": "Larry"
},
{
	"birthdate": "1995",
	"name": "Nicole"
},
{
	"birthdate": "1996",
	"name": "Jane"
},
{
	"birthdate": "1996",
	"name": "Janet"
},
{
	"birthdate": "1996",
	"name": "Dora"
},
];

const res = arr.reduce((ac, a) => {
let temp = ac.find(x => x.birthdate === a.birthdate);
if (!temp) ac.push({ ...a,
	name: [a.name]
})
else temp.name.push(a.name)
return ac;
}, [])
console.log(res);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.5/lodash.min.js"></script>

Answer 3

您可以链接 groupBy 和 map 来实现这一点。

_.chain(yourArray)
.groupBy('birthdate')
.toPairs()
.map(s=>{
return _.zipObject(['birthdate','names'],s)
})
.map(s=>{
s.names=_.map(s.names,x=>x.name);
return s;
})
.value()

Answer 4

一个简单且可自定义的纯 javascript 函数，用于返回按对象所需属性分组的对象数组

export const groupArrayBy = (arr, groupBy) => {

    let newArr = []
    arr.map((item) => {
        if(item[groupBy]) {
            let finded = newArr.filter((newItem) => newItem[groupBy] === item[groupBy])
            if(finded.length > 0) {
                finded[0].products.push(item)
            } else {
                newArr.push({category: item[groupBy], products: [item]})
            }
        }
    })

    return newArr
}

Answer 5

Lodash 简写

var data=[
    { "birthdate": "1993", "name": "Ben" },
    { "birthdate": "1994", "name": "John" },
    { "birthdate": "1995", "name": "Larry" },
    { "birthdate": "1995", "name": "Nicole" },
    { "birthdate": "1996", "name": "Jane" },
    { "birthdate": "1996", "name": "Janet" },
    { "birthdate": "1996", "name": "Dora" },
];


var list= _(data)
    .groupBy('birthdate')
    .map((items, birthdate)=> ({birthdate: birthdate,names: _.map(items, 'name')
      })).value();
      
      console.log(list)

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.5/lodash.min.js"></script>