LoDash挑战，我有我需要过滤对象的数组，对值数组 [英] LoDash challenges, I have an array of objects I need to filter, for an array of values

问题描述

我有我需要通过 _id 使用 _id 值数组来过滤以下对象数组。

  VAR对象= {[
    _account：YzzrzBrO9OSzo6BXwAvVuL5dmMKMqkhOoEqeo
    _id：055z5gzVyVfzlBnEOqYvcoLL1ZgOWJhkrWMkv2
}，{
    _account：YzzrzBrO9OSzo6BXwAvVuL5dmMKMqkhOoEqeo
    _id：LvvrvyrOGOS2e5yE0Bdki45Y1ndVlgfoZ2zoOp
}，{
    _account：mjj9jp92z2fD1mLlpQYZI1gAd4q4LwTKmBNLz
    _id：rEEwENwnznCQvkm61wRziKlMRPqaYztnR4vn61
}，{
    _account：AaaraZrLqLfzRYoAPlb6ujPELWVW4dTK4eJWj
    _id：944r40rPgPU2nXqzMYolS5nyo6Eo9OuqrlDkB
}，{
    _account：AaaraZrLqLfzRYoAPlb6ujPELWVW4dTK4eJWj
    _id：rEEwENwnznCQvkm61wZ9uey62Pjy5YTqgYGDK
}];VAR id_values​​ = [
    rEEwENwnznCQvkm61wZ9uey62Pjy5YTqgYGDK
    944r40rPgPU2nXqzMYolS5nyo6Eo9OuqrlDkB
    rEEwENwnznCQvkm61wRziKlMRPqaYztnR4vn61
];
 

我相信区别，拉或无可能是有用的，但我不能从LoDash文档区分它们。我也觉得的forEach ， forIn 或 uniq的可能是有用的。我能够过滤的对象之一了使用拒绝：

  _。拒绝（对象，{
    _id：rEEwENwnznCQvkm61wZ9uey62Pjy5YTqgYGDK
}）;
 

不过这并不能帮助我需要通过一个数组进行筛选。结果应该是以下数组：

  VAR的结果= [{
    _account：YzzrzBrO9OSzo6BXwAvVuL5dmMKMqkhOoEqeo
    _id：055z5gzVyVfzlBnEOqYvcoLL1ZgOWJhkrWMkv2
}，{
    _account：YzzrzBrO9OSzo6BXwAvVuL5dmMKMqkhOoEqeo
    _id：LvvrvyrOGOS2e5yE0Bdki45Y1ndVlgfoZ2zoOp
}];
 

解决方案

这是我知道如何使用LoDash做最快的方式：

\r

\r

VAR对象= {[\r
    _account：YzzrzBrO9OSzo6BXwAvVuL5dmMKMqkhOoEqeo\r
    _id：055z5gzVyVfzlBnEOqYvcoLL1ZgOWJhkrWMkv2\r
}，{\r
    _account：YzzrzBrO9OSzo6BXwAvVuL5dmMKMqkhOoEqeo\r
    _id：LvvrvyrOGOS2e5yE0Bdki45Y1ndVlgfoZ2zoOp\r
}，{\r
    _account：mjj9jp92z2fD1mLlpQYZI1gAd4q4LwTKmBNLz\r
    _id：rEEwENwnznCQvkm61wRziKlMRPqaYztnR4vn61\r
}，{\r
    _account：AaaraZrLqLfzRYoAPlb6ujPELWVW4dTK4eJWj\r
    _id：944r40rPgPU2nXqzMYolS5nyo6Eo9OuqrlDkB\r
}，{\r
    _account：AaaraZrLqLfzRYoAPlb6ujPELWVW4dTK4eJWj\r
    _id：rEEwENwnznCQvkm61wZ9uey62Pjy5YTqgYGDK\r
}];\r
\r
VAR id_values​​ = [\r
    rEEwENwnznCQvkm61wZ9uey62Pjy5YTqgYGDK\r
    944r40rPgPU2nXqzMYolS5nyo6Eo9OuqrlDkB\r
    rEEwENwnznCQvkm61wRziKlMRPqaYztnR4vn61\r
];\r
\r
VAR指数= index_of_array（id_values​​）;\r
\r
VAR的结果= _.reject（对象，函数（对象）{\r
    回报指数[object._id] ||假;\r
}）;\r
\r
的console.log（结果）;

\r

＆LT;脚本SRC =htt​​p://cdn.jsdelivr.net/lodash /2.1.0/lodash.compat.js\"></script>\r
\r
＆LT;脚本＆GT;\r
/ *\r
  创建键阵列的索引。允许您检查数组是否\r
  在O（1）时间特定的键（相对于o使用的indexOf（n）的时间）。它\r
  需要O（n）的时间来创建其中n是阵列的长度的索引。\r
\r
  例如\r
\r
  变种键= [1,2,3];\r
  VAR指数= index_of_array（键）; // 准时\r
  的console.log（指数[1] ||假）; //真 - O（1）时间\r
  的console.log（指数[4] ||假）; //假 - O（1）时间\r
  的console.log（keys.indexOf（1）＆GT = 0）; //真 - O（n）的时间\r
  的console.log（keys.indexOf（4）＆GT = 0）; //假 - O（n）的时间\r
* /\r
\r
功能index_of_array（阵列）{\r
    VAR长度= array.length\r
      ，结果= {}\r
      ，索引= 0;\r
\r
    而（指数＆LT;长度）\r
        结果[数组[索引++] = TRUE;\r
    返回结果;\r
}\r
＆LT; / SCRIPT＆GT;

\r

\r

\r

希望有所帮助。

I have the following array of objects that I need to filter by _id using an array of _id values.

var objects = [{
    _account: "YzzrzBrO9OSzo6BXwAvVuL5dmMKMqkhOoEqeo",
    _id:      "055z5gzVyVfzlBnEOqYvcoLL1ZgOWJhkrWMkv2"
}, {
    _account: "YzzrzBrO9OSzo6BXwAvVuL5dmMKMqkhOoEqeo",
    _id:      "LvvrvyrOGOS2e5yE0Bdki45Y1ndVlgfoZ2zoOp"
}, {
    _account: "mjj9jp92z2fD1mLlpQYZI1gAd4q4LwTKmBNLz",
    _id:      "rEEwENwnznCQvkm61wRziKlMRPqaYztnR4vn61"
}, {
    _account: "AaaraZrLqLfzRYoAPlb6ujPELWVW4dTK4eJWj",
    _id:      "944r40rPgPU2nXqzMYolS5nyo6Eo9OuqrlDkB"
}, {
    _account: "AaaraZrLqLfzRYoAPlb6ujPELWVW4dTK4eJWj",
    _id:      "rEEwENwnznCQvkm61wZ9uey62Pjy5YTqgYGDK"
}];

var id_values = [
    "rEEwENwnznCQvkm61wZ9uey62Pjy5YTqgYGDK",
    "944r40rPgPU2nXqzMYolS5nyo6Eo9OuqrlDkB",
    "rEEwENwnznCQvkm61wRziKlMRPqaYztnR4vn61"
];

I believe that difference, pull or without could be useful but I can't tell them apart from the documentation on LoDash. I also think forEach, forIn or uniq could be useful. I was able to filter one of the objects out using reject:

_.reject(objects, {
    _id: "rEEwENwnznCQvkm61wZ9uey62Pjy5YTqgYGDK"
});

Still this does not help me with the need to filter by an array. The result should be the following array:

var result = [{
    _account: "YzzrzBrO9OSzo6BXwAvVuL5dmMKMqkhOoEqeo",
    _id:      "055z5gzVyVfzlBnEOqYvcoLL1ZgOWJhkrWMkv2"
}, {
    _account: "YzzrzBrO9OSzo6BXwAvVuL5dmMKMqkhOoEqeo",
    _id:      "LvvrvyrOGOS2e5yE0Bdki45Y1ndVlgfoZ2zoOp"
}];

解决方案

This is the fastest way I know how to do it using LoDash:

var objects = [{
    _account: "YzzrzBrO9OSzo6BXwAvVuL5dmMKMqkhOoEqeo",
    _id:      "055z5gzVyVfzlBnEOqYvcoLL1ZgOWJhkrWMkv2"
}, {
    _account: "YzzrzBrO9OSzo6BXwAvVuL5dmMKMqkhOoEqeo",
    _id:      "LvvrvyrOGOS2e5yE0Bdki45Y1ndVlgfoZ2zoOp"
}, {
    _account: "mjj9jp92z2fD1mLlpQYZI1gAd4q4LwTKmBNLz",
    _id:      "rEEwENwnznCQvkm61wRziKlMRPqaYztnR4vn61"
}, {
    _account: "AaaraZrLqLfzRYoAPlb6ujPELWVW4dTK4eJWj",
    _id:      "944r40rPgPU2nXqzMYolS5nyo6Eo9OuqrlDkB"
}, {
    _account: "AaaraZrLqLfzRYoAPlb6ujPELWVW4dTK4eJWj",
    _id:      "rEEwENwnznCQvkm61wZ9uey62Pjy5YTqgYGDK"
}];

var id_values = [
    "rEEwENwnznCQvkm61wZ9uey62Pjy5YTqgYGDK",
    "944r40rPgPU2nXqzMYolS5nyo6Eo9OuqrlDkB",
    "rEEwENwnznCQvkm61wRziKlMRPqaYztnR4vn61"
];

var index  = index_of_array(id_values);

var result = _.reject(objects, function (object) {
    return index[object._id] || false;
});

console.log(result);

<script src="http://cdn.jsdelivr.net/lodash/2.1.0/lodash.compat.js"></script>

<script>
/*
  Creates an index of an array of keys. Allows you to check whether the array
  has a specific key in O(1) time (as compared to O(n) time using indexOf). It
  takes O(n) time to create the index where n is the length of the array.

  e.g.

  var keys  = [1,2,3];
  var index = index_of_array(keys);     //         O(n) time
  console.log(index[1] || false);       // true  - O(1) time
  console.log(index[4] || false);       // false - O(1) time
  console.log(keys.indexOf(1) >= 0);    // true  - O(n) time
  console.log(keys.indexOf(4) >= 0);    // false - O(n) time
*/

function index_of_array(array) {
    var length = array.length
      , result = {}
      , index  = 0;

    while (index < length)
        result[array[index++]] = true;
    return result;
}
</script>

Hope that helps.

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