过滤数组以具有唯一值[重复]

Question

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"]

预期结果应该是

["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

Answer 1

indexOf 方法的细微变化，如果您需要过滤多个数组：

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

这样使用：

arr.filter(unique);

Answer 2

您可以使用Array.filter 函数根据回调函数的返回值过滤掉数组中的元素。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，因此可以认为是唯一的。如果没有，则表示该元素已经遇到过，所以现在应该丢弃。

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 cmets 中的 rob 所指出的，这种方法应该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 features，那么您可以使用Set object 和Spread operator 从给定数组创建一个唯一数组，正如下面@Travis Heeter 的回答中所述：

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

Answer 3

据我所知，这适用于es2015 及以上。 ES6 有“更清洁”的选项，但这是一个很好的方法（TypeScript）。

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

Answer 4

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

那么我们可以写：

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

Answer 5

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

Array.from(new Set(arrayOfNonUniqueValues));

Set

Set 对象允许您存储任何类型的唯一值，无论是 原始值或对象引用。

返回值一个新的 Set 对象。

Array.from()

Array.from() 方法从一个 类数组或可迭代对象。

返回值一个新的 Array 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);

Answer 6

我一直用：

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

但最近我不得不为：

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

而我的旧待机并没有削减它，所以我想出了这个：

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

Answer 7

您可以使用哈希表来查找和过滤所有未包含的值。

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);

Answer 8

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}`)

Answer 9

从 2015 年 6 月 15 日起，您可以使用 Set() 创建唯一数组：

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

---

你的例子：

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"]

Answer 10

您可以使用Map 和Spread Operator：

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);

Answer 11

您可以使用reduce 循环数组并获取不重复的值。还使用 aux 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);