如何使用 lodash 或 javascript 按数组分组

Question

一个数组如下：

let names = [

             'Aditya',

             'Aditya',

             'Aditya',

             'Abhi',

             'Abhi',

             'goyal'

            ]

我想使用 lodash 函数并转换将返回我的名称数组

[

  Aditya(3),

  Abhi(2),

  goyal(1)

]

Answer 1

您可以使用_.countBy()来获取带有计数的名称对象，或者_.groupBy()如果您想要带有数组的名称对象。使用_.groupBy()and的数组数组_.values()：const names = ["Aditya","Aditya","Aditya","Abhi","Abhi","goyal"]const result = _.values(_.groupBy(names))console.log(result)<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.js"></script>和计数的对象_.countBy：const names = ["Aditya","Aditya","Aditya","Abhi","Abhi","goyal"]const result = _.countBy(names)console.log(result)<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.js"></script>更新 - 要获取组合键和值的字符串数组，您可以使用_.countBy()，然后使用_.map()它（lodash 也_.map()适用于对象）。const names = ["Aditya","Aditya","Aditya","Abhi","Abhi","goyal"]const result = _.map(_.countBy(names), (v, k) => `${k}(${v})`)console.log(result)<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.js"></script>

Answer 2

1)_.countBy生成对象的名称，名称/计数作为键/值。2)_.entries用于将对象转换为一组嵌套条目数组。3）_.map在条目上产生所需的输出。const names = ["Aditya","Aditya","Aditya","Abhi","Abhi","goyal"]const toString = ([name, count]) => `${name}(${count})`;const entries = _.entries(_.countBy(names));const result = _.map(entries, toString);console.log(result);<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.js"></script>另外，您可以用香草JS实现使用（几乎）相同数量的代码同样的事情reduce，Object.entries和map。const names = ["Aditya","Aditya","Aditya","Abhi","Abhi","goyal"]const counts = names.reduce((acc, c) => {&nbsp; return acc[c] = (acc[c] || 0) + 1, acc;}, {});const toString = ([name, count]) => `${name}(${count})`;const entries = Object.entries(counts);const result2 = entries.map(toString);console.log(result2);