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将值从一个数组分配到嵌套数组的最有效方法

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random_user_name · 技术社区 · 6 年前

给定集合( users 在下面的代码片段中)包含子集合和另一个集合( organizations )其中包含我需要合并到的子集合中的属性 用户 ,最有效的方法是什么?

下面的代码可以工作,但是嵌套迭代对我来说从来没有那么好的感觉。此外,生产环境有成百上千个结果,因此至少要考虑性能。

仅供参考,我正在利用 lodash 图书馆,我知道会从不不过,我希望有人能提供一种更有效的方法来解决这个问题。

下面的代码查找组织的名称,然后将该名称添加到 用户 用于应用程序其他部分的数组。

(数据结构来自API,不能更改。)

// organizations are actually fetched from an API via Observable.  Can change at any time.
const organizations = [{
    organization_id: 5,
    organization_name: 'Sample 1'
  },
  {
    organization_id: 6,
    organization_name: 'Sample 2'
  },
  {
    organization_id: 9,
    organization_name: 'Sample 3'
  },
  // etc...
];

// users are actually fetched from an API via Observable.  Can change at any time.
const users = [{
    user_name: 'User 1',
    organizations: [{
        organization_id: 9,
        organization_role: 'Limited'
      },
      {
        organization_id: 6,
        organization_role: 'Admin'
      }
    ]
  },
  {
    user_name: 'User 2',
    organizations: [{
        organization_id: 5,
        organization_role: 'Limited'
      },
      {
        organization_id: 6,
        organization_role: 'Limited'
      }
    ]
  },
  // etc...
];


document.addEventListener('DOMContentLoaded', () => {
  _.forEach(users, (user) => {
    _.forEach(user.organizations, (organization) => {
      organization.organization_name = _.get(_.find(organizations, ['organization_id', organization.organization_id]), 'organization_name', '?');
    });
  });
  console.log(users);
}, false);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.min.js"></script>

1 回复 | 直到 6 年前

Ori Drori 6 年前

自从 _.find() 是O(n)操作(其中n是组织常数的长度),for each操作o(m*l)(m用户数,l每个用户的平均组织数),总操作为O(n*m*l)。您可以通过首先映射组织将其降低为O(n+m*l),这是O(n)操作(使用 _.keyBy() 例如)。

// organizations are actually fetched from an API via Observable.  Can change at any time.
const organizations = [{"organization_id":5,"organization_name":"Sample 1"},{"organization_id":6,"organization_name":"Sample 2"},{"organization_id":9,"organization_name":"Sample 3"}];

// users are actually fetched from an API via Observable.  Can change at any time.
const users = [{"user_name":"User 1","organizations":[{"organization_id":9,"organization_role":"Limited"},{"organization_id":6,"organization_role":"Admin"}]},{"user_name":"User 2","organizations":[{"organization_id":5,"organization_role":"Limited"},{"organization_id":6,"organization_role":"Limited"}]}];


document.addEventListener('DOMContentLoaded', () => {
  const orgDict = _.keyBy(organizations, 'organization_id');
  _.forEach(users, (user) => {
    _.forEach(user.organizations, (organization) => {
      organization.organization_name = _.get(orgDict['organization_id'], 'organization_name', '?');
    });
  });
  console.log(users);
}, false);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.min.js"></script>