如何在数组中查找出现次数最多的项目 [英] How to find an item in array which has the most occurrences

问题描述

如何在数组中找到出现次数最多的项目?

How do I find an item in array which has the most occurrences?

[1, 1, 1, 2, 3].mode
=> 1

['cat', 'dog', 'snake', 'dog'].mode
=> dog

推荐答案

首先构建一个哈希，将数组中的每个值映射到其频率…

First build a hash mapping each value in the array to its frequency…

arr = [1, 1, 1, 2, 3]

freq = arr.inject(Hash.new(0)) { |h,v| h[v] += 1; h }
#=> {1=>3, 2=>1, 3=>1}

…然后使用频率表查找频率最高的元素:

… then use the frequency table to find the element with the highest frequency:

arr.max_by { |v| freq[v] }
#=> 1

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