Javascript Lodash按外部数组和内部属性排序

Question

我有一个人员数组，需要先按定义的外部数组(order)排序，然后再按年龄排序。我正在使用lodash sortBy

const _  = require('lodash');
const arr = [
  { name: "Mandy", age: "34" },
  { name: "Shelly", age: "32" },
  { name: "Kyle", age: "12" },
  { name: "Kyle", age: "60" },
  { name: "Mandy", age: "32" },
  { name: "Mandy", age: "99" },
  { name: "Shelly", age: "30" },
  { name: "John", age: "3" },
  { name: "John", age: "1" },
  { name: "John", age: "6" },
  { name: "Mandy", age: "3" }
];

let order = ["Shelly", "John", "Mandy", "Kyle"];

let sortedArrByOrder = _.sortBy(arr, [person => order.indexOf(person.name), 'age'], ['asc', 'desc']);

console.log(sortedArrByOrder);

但是年龄不是按降序排序的。有没有办法让它工作呢？

Answer 1

_.sortBy()不排除order (asc / desc)，改用_.orderBy()：

​

const arr = [{ name: "Mandy", age: "34" },{ name: "Shelly", age: "32" },{ name: "Kyle", age: "12" },{ name: "Kyle", age: "60" },{ name: "Mandy", age: "32" },{ name: "Mandy", age: "99" },{ name: "Shelly", age: "30" },{ name: "John", age: "3" },{ name: "John", age: "1" },{ name: "John", age: "6" },{ name: "Mandy", age: "3" }];

const order = ["Shelly", "John", "Mandy", "Kyle"];

const sortedArrByOrder = _.orderBy(arr, [person => order.indexOf(person.name), 'age'], ['asc', 'desc']);

console.log(sortedArrByOrder);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.js"></script>

​

此外，在排序操作中使用Array.indexOf() (O(n)) (对于包含10个以上项的数组，使用O(NLogn))可能会影响性能。更好的方法是将order数组转换为具有O(1)检索的数据结构(如映射或纯对象)，并存储数组中的原始索引。现在您可以直接获取原始索引：

​

const arr = [{ name: "Mandy", age: "34" },{ name: "Shelly", age: "32" },{ name: "Kyle", age: "12" },{ name: "Kyle", age: "60" },{ name: "Mandy", age: "32" },{ name: "Mandy", age: "99" },{ name: "Shelly", age: "30" },{ name: "John", age: "3" },{ name: "John", age: "1" },{ name: "John", age: "6" },{ name: "Mandy", age: "3" }];

const order = new Map(["Shelly", "John", "Mandy", "Kyle"].map((s, i) => [s, i]))

const sortedArrByOrder = _.orderBy(arr, [person => order.get(person.name), 'age'], ['asc', 'desc']);

console.log(sortedArrByOrder);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.js"></script>

​

Answer 2

您可以接受回调并返回负年龄，并省略订单的数组。

​

const
    arr = [{ name: "Mandy", age: "34" }, { name: "Shelly", age: "32" }, { name: "Kyle", age: "12" }, { name: "Kyle", age: "60" }, { name: "Mandy", age: "32" }, { name: "Mandy", age: "99" }, { name: "Shelly", age: "30" }, { name: "John", age: "3" }, { name: "John", age: "1" }, { name: "John", age: "6" }, { name: "Mandy", age: "3" }],
    order = ["Shelly", "John", "Mandy", "Kyle"],
    sortedArrByOrder = _.sortBy(arr, [
        ({ name }) => order.indexOf(name),
        ({ age }) => -age
    ]);

console.log(sortedArrByOrder);

.as-console-wrapper { max-height: 100% !important; top: 0; }

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.min.js"></script>

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