Question

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 

Answer 1

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} 

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

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