Question

This will return the first instance of the longest string in an array:

["abcd","efgh","ijk"].max_by { |x| x.length } # => "abcd"

Similarly to this, is there a nice way to get an array of all strings with the maximal length?

["abcd","efgh","ijk"].some_trick ... # => ["abcd","efgh"]

Answer 1

Here we go :

["abcd","efgh","ijk"].group_by(&:size).max.last #=> ["abcd","efgh"]

Explanation :

• Enumerable#group_by gives a hash containing each unique size of strings contained in the array as keys, and the matching strings as values => {4=>["abcd", "efgh"], 3=>["ijk"]}
• Enumerable#max applied on a Hash will give us the highest key with its matching values, in an Array like this : [key, values] => [4, ["abcd", "efgh"]]
• Array#last will give us the last element of the array … => ["abcd", "efgh"]