比较和过滤两个 arrays

Question

我一直在尝试实现一个 function，其中有两个 arrays，

array1的元素用作过滤掉array2中元素的条件。

例如：

array1= [apple, grapes, oranges]

array2= [potato, pears, grapes, berries, apples, oranges]

在输入 function 后，array2 应该有这样的元素：

filter_twoArrays(array1,array2)

array2= [grapes, apples, oranges]

我尝试了以下代码，使用 for 循环和 array.splice()，但我看到的问题是，当我使用 splice 方法时，它似乎改变了 for 循环中 array2 的长度：

function filter_twoArrays(filter,result){

  for(i=0; i< filter.length; i++){
    for(j=0; j< result.length; j++){
      if(filter[i] !== result[j]){
        result.splice(j,1)
      }
    }
  }

任何关于如何改进过滤器的输入将不胜感激 function

干杯！

Answer 1

您可以使用过滤器如下

 var array1 = ['apples', 'grapes', 'oranges', 'banana'], array2 = ['potato', 'pears', 'grapes', 'berries', 'apples', 'oranges']; var intersection = array1.filter(function(e) { return array2.indexOf(e) > -1; }); console.log(intersection);

也可以在 Array 原型上添加这个方法，直接在数组上调用

 Array.prototype.intersection = function(arr) { return this.filter(function(e) { return arr.indexOf(e) > -1; }); }; var array1 = ['apples', 'grapes', 'oranges', 'banana'], array2 = ['potato', 'pears', 'grapes', 'berries', 'apples', 'oranges']; var intersection = array1.intersection(array2); console.log(intersection);

Answer 2

嗨，这是函数 array_intersect php 的移植。 应该对你有好处http://phpjs.org/functions/array_intersect/

function array_intersect(arr1) {
  //  discuss at: http://phpjs.org/functions/array_intersect/
  // original by: Brett Zamir (http://brett-zamir.me)
  //        note: These only output associative arrays (would need to be
  //        note: all numeric and counting from zero to be numeric)
  //   example 1: $array1 = {'a' : 'green', 0:'red', 1: 'blue'};
  //   example 1: $array2 = {'b' : 'green', 0:'yellow', 1:'red'};
  //   example 1: $array3 = ['green', 'red'];
  //   example 1: $result = array_intersect($array1, $array2, $array3);
  //   returns 1: {0: 'red', a: 'green'}

  var retArr = {},
    argl = arguments.length,
    arglm1 = argl - 1,
    k1 = '',
    arr = {},
    i = 0,
    k = '';

  arr1keys: for (k1 in arr1) {
    arrs: for (i = 1; i < argl; i++) {
      arr = arguments[i];
      for (k in arr) {
        if (arr[k] === arr1[k1]) {
          if (i === arglm1) {
            retArr[k1] = arr1[k1];
          }
          // If the innermost loop always leads at least once to an equal value, continue the loop until done
          continue arrs;
        }
      }
      // If it reaches here, it wasn't found in at least one array, so try next value
      continue arr1keys;
    }
  }

  return retArr;
}

Answer 3

你可以使用some ，像这样：

let newArray = array2.filter(
      (array22) => !array1.some((array11) => array11.id === array22._id));

Answer 4

由于您已在此处标记 javascript，因此这是解决方案。

function f1(x, y) {
    var t = y.slice(0);
    var r = [];
    for (var i = 0; i < x.length; i++) {
        for (var j = 0; j < y.length; j++) {
            if (x[i] === y[j]) {
                [].push.apply(r, t.splice(j, 1));
            }
        }
    }
    console.log(r)
    y.length = 0;
    [].push.apply(y, r);
}

Answer 5

这是一种基于您的代码的简单方法

function array_filter(filter, result) {
    var filterLen = filter.length;
    var resultLen = result.length;

    for (i = 0; i < resultLen; i++) {
        for (j = 0; j < filterLen; j++) {
            if (!contains(filter, result[i]))
                result.splice(i, 1);
        }
    }
}

//Return boolean depending if array 'a' contains item 'obj'
function contains(array, value) {
    for (var i = 0; i < array.length; i++) {
        if (array[i] == value) {
            return true;
        }
    }
    return false;
}

Answer 6

标记要通过delete result[index]过滤掉的项目，根据需要对其进行操作。

JavaScript

window.onload = runs;

function runs() {
    var array1 = ["apples", "grapes", "oranges"];
    var array2 = ["potato", "pears", "grapes", "berries", "apples", "oranges"];
    var result = filter_twoArrays(array1, array2);

    function filter_twoArrays(filter, result) {
        var i = 0,
            j = 0;
        for (i = 0; i < result.length; i++) {
            var FLAG = 0;
            for (j = 0; j < filter.length; j++) {
                if (filter[j] == result[i]) {
                    FLAG = 1;
                }
            }
            if (FLAG == 0) delete result[i];
        }
        return result;
    }

    var body = document.getElementsByTagName("body")[0];
    var i = 0;
    for (i = 0; i < result.length; i++) {
        if (result[i] !== undefined)
            body.innerHTML = body.innerHTML + result[i] + " ";
    }
}

Answer 7

您可以使用

const arr1 = [1, 2, 3];
const arr2 = [2, 3];

arr1.filter(e => arr2.indexOf(e) > -1 ? false : true); // [1]

Answer 8

一周前来到这里寻找解决此类问题的方法，但很遗憾我无法得到我想要的东西，但现在我以更简单的方式解决了问题。 使用箭头函数、 .filter()方法和.includes()方法。

声明一个接受两个参数的箭头函数：

const filterTwoArrays = (string1, string2) => string1.filter(item => string2.includes(item));

console.log(filterTwoArrays(array1, array2)).

Answer 9

const func = array1.filter(item => array2.includes(item));