查找数组中出现频率最高的项(不仅仅是字符串) [英] Find the most frequent item of an array (not just strings)

问题描述

有人可以指导我完成这个练习吗?编写一个 JavaScript 程序来查找数组中最频繁的项.

Can someone walk me through this exercise? Write a JavaScript program to find the most frequent item of an array.

var arr1 = [3, 'a', 'a', 'a', 2, 3, 'a', 3, 'a', 2, 4, 9, 3];
var mf = 1;
var m = 0;
var item;

for (var i = 0; i < arr1.length; i++) {
  for (var j = i; j < arr1.length; j++) {
    if (arr1[i] == arr1[j]) m++;
    if (mf < m) {
      mf = m;
      item = arr1[i];
    }
  }

  m = 0;
}

alert(item + " ( " + mf + " times ) ");

我一直在查看有关 stackoverflow 的一些类似问题，只是找不到我想要的答案.

I've been checking out some similar questions on stackoverflow, just can't find the answers that I want.

我的问题是:

1. 我不明白为什么需要有两个 for 循环.

1. I don't understand why there needs to have two for loops.

为什么需要 mf 和 m.看起来有点混乱.

Why the need for mf and m. Seems a bit confusing.

有没有其他解决方法?

推荐答案

我真的不认为在这个解决方案中需要 2 个循环.你可以看看这个原型代码，它使用了一个叫做 map 的简单数据结构:

I really do not think there is a need for 2 loops in this solution. You can look at this prototyping code which uses a simple data structure called map:

var arr=[3, 'a', 'a', 'a', 2, 3, 'a', 3, 'a', 2, 4, 9, 3];
var map = {};
var mostFrequentElement = arr[0];
function findMostFrequent(){
    for(var i = 0; i<arr.length; i++){
        if(!map[arr[i]]){
            map[arr[i]]=1;
        }else{
            ++map[arr[i]];
            if(map[arr[i]]>map[mostFrequentElement]){
                mostFrequentElement = arr[i];
            }
        }
    }
    alert(mostFrequentElement);
}

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