筛选数组以具有唯一值

Filter array to have unique values

本文关键字：唯一 数组 筛选      更新时间：2023-09-26

我需要过滤掉我的数组以仅包含唯一值。这是我的数组数据

["X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11"]

预期结果应为

["X_row7", "X_row4", "X_row6", "X_row10", "X_row11", "X_row8", "X_row9"]

我应该如何继续我的代码以获得正确的结果。

newArray = [];
for(n in data){
  if(!newArray.indexOf(n)){
     newArray.push(n);
  }
}
console.log(newArray);

如果您需要任何其他信息，请告诉我，我会提供。

谢谢

您可以使用 Array.filter 函数根据回调函数的返回值过滤掉数组的元素。回调函数针对原始数组的每个元素运行。

这里回调函数的逻辑是，如果当前项的indexOf值与索引相同，则表示该元素是第一次遇到的，因此可以认为它是唯一的。如果没有，则表示该元素已经遇到，因此现在应该丢弃。

var arr = ["X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11"];
var filteredArray = arr.filter(function(item, pos){
  return arr.indexOf(item)== pos; 
});
console.log( filteredArray );

警告：正如 rob 在评论中指出的那样，此方法应避免使用非常大的数组，因为它在 O(N^2) 中运行。

更新 (2017年11月16日(

如果您可以依赖 ES6 功能，那么您可以使用 Set 对象和 Spread 运算符从给定数组创建一个唯一的数组，如下面 Heeter @Travis答案中所述：

var uniqueArray = [...new Set(array)]

自 2015 年 6 月 15 日起，您可以使用 Set() 创建一个唯一的数组：

var uniqueArray = [...new Set(array)]

对于您的示例：

var data = ["X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11"]
var newArray = [...new Set(data)]
console.log(newArray)
>> ["X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11"]

使用 JavaScript Set 和 Array.from 方法可以过滤数组以包含唯一值，如下所示：

Array.from(new Set(arrayOfNonUniqueValues));

设置

Set 对象允许您存储任何类型的唯一值，无论 基元值或对象引用。

返回值 一个新的 Set 对象。

Array.from((

Array.from(( 方法从 类数组或可迭代对象。

返回值 一个新的数组实例。

示例代码：

const array = ["X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11"]
const uniqueArray = Array.from(new Set(array));
console.log("uniqueArray: ", uniqueArray);

arr = ["I", "do", "love", "JavaScript", "and", "I", "also", "do", "love", "Java"];
uniqueArr = [... new Set(arr)];
// or
reallyUniqueArr = arr.filter((item, pos, ar) => ar.indexOf(item) === pos)
console.log(`${uniqueArr}'n${reallyUniqueArr}`)

您可以使用哈希表进行查找和筛选所有未包含的值。

var data = ["X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11"],
    unique = data.filter(function (a) {
        return !this[a] && (this[a] = true);
    }, Object.create(null));
console.log(unique);

Array.prototype.unique = function () {
  return [...new Set(this)]
}

然后我们可以写：

const arr = [1, 5, 2, 2, 2, 3, 4, 3, 2, 1, 5]
const uniqueArr = arr.unique()

您可以使用"地图和展开"运算符：

var rawData = ["X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11"];
var unique = new Map();
rawData.forEach(d => unique.set(d, d));
var uniqueItems = [...unique.keys()];
console.log(uniqueItems);

据

我所知，这是针对es2015及以上。ES6有"更干净"的选项，但这是一个很好的方法(使用 TypeScript (。

let values: any[] = [];
const distinct = (value: any, index: any, self: any) => {
    return self.indexOf(value) === index;
};
values = values.filter(distinct);
您可以使用

reduce循环数组并获取不重复的值。还使用辅助object来获取附加值的计数。

var aux = {};
var newArray = ["X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11", "X_row7", "X_row4", "X_row6", "X_row10", "X_row8", "X_row9", "X_row11"].reduce((tot, curr)=>{
  if(!aux[curr]){
    aux[curr] = 1;
    tot.push(curr);
  }
  return tot;
}, []);
console.log(newArray);

如果需要过滤多个数组，则indexOf方法略有不同：

function unique(item, index, array) {
    return array.indexOf(item) == index;
}

这样使用：

arr.filter(unique);

我一直使用：

unique = (arr) => arr.filter((item, i, s) => s.lastIndexOf(item) == i);

但最近我必须获得以下各项的唯一值：

["1", 1, "2", 2, "3", 3]

而且我的旧备用没有削减它，所以我想出了这个：

uunique = (arr) => Object.keys(Object.assign({}, ...arr.map(a=>({[a]:true}))));
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