Javascript根据另一个索引重新索引数组

Question

试图弄清楚。不能。我有 2 个数组，我想对其中一个数组的索引进行排序，以匹配其对象的索引。

数组 1 是这样的：

var arr1 = [
  {
   "name": "bobby",
   "occupation": "singer"
  },
  {
   "name": "mindy",
   "occupation": "artist"
  }
] 

和数组 2：

var arr2 = [
  {
   "name": "mindy",
   "hobby": "drawing"
  },
  {
   "name": "bobby",
   "hobby": "driving"
  }
]

重新索引哪个并不重要。关键是我有两个名字bobby 和mindy，我想重新排列其中一个数组，以便它们的索引与另一个匹配。

Answer 1

将sort 与compareFunction 一起使用。

在下面找到内联的 cmets。

var arr1 = [
  {
   "name": "bobby",
   "occupation": "singer"
  },
  {
   "name": "mindy",
   "occupation": "artist"
  }
] 

var arr2 = [
  {
   "name": "mindy",
   "hobby": "drawing"
  },
  {
   "name": "bobby",
   "hobby": "driving"
  }
]

// create intermediate array of arr2 names
arr2Names = arr2.map(x => x.name)

// use sort:
arr1 = arr1.sort((x,y) => arr2Names.indexOf(x.name) - arr2Names.indexOf(y.name))
console.log(arr1, arr2)

var arr2 = ['a', 'b', 'c', 'd', 'e', 'f', 'g']
var arr1 = ['b', 'd', 'g', 'f', 'e', 'a', 'c']
console.log(arr1.sort((x,y) => arr2.indexOf(x)  - arr2.indexOf(y)))

Answer 2

通常的 (?) 简短版本是 O(n²)（假设所有名称都是唯一的并且存在于两个数组中）：

var arr1 = [ { "name": "bobby", "occupation": "singer" },
             { "name": "mindy", "occupation": "artist" } ]; 
var arr2 = [ { "name": "mindy", "hobby": "drawing" },
             { "name": "bobby", "hobby": "driving" } ];

var arr2 = arr1.map(a => arr2.find(b => a.name === b.name));

console.log( JSON.stringify(arr1).replace('},', '},\n ') );
console.log( JSON.stringify(arr2).replace('},', '},\n ') );

按名称对两个数组进行排序是O(n log n)：

var arr1 = [ { "name": "bobby", "occupation": "singer" },
             { "name": "mindy", "occupation": "artist" } ]; 
var arr2 = [ { "name": "mindy", "hobby": "drawing" },
             { "name": "bobby", "hobby": "driving" } ];

arr1.sort((a, b) => a.name.localeCompare(b.name));
arr2.sort((a, b) => a.name.localeCompare(b.name));

console.log( JSON.stringify(arr1).replace('},', '},\n ') );
console.log( JSON.stringify(arr2).replace('},', '},\n ') );

最后，使用查找助手对象的 O(n) 版本：

var arr1 = [ { "name": "bobby", "occupation": "singer" },
             { "name": "mindy", "occupation": "artist" } ]; 
var arr2 = [ { "name": "mindy", "hobby": "drawing" },
             { "name": "bobby", "hobby": "driving" } ];

var lookup = arr2.reduce((r, v) => (r[v.name] = v, r), {});
var arr2 = arr1.map(v => lookup[v.name]);

console.log( JSON.stringify(arr1).replace('},', '},\n ') );
console.log( JSON.stringify(arr2).replace('},', '},\n ') );