Question:

Write a function that sorts the keys in a hash by the length of the key as a string. For instance, the hash:

{ abc: 'hello', 'another_key' => 123, 4567 => 'third' }

should result in:

["abc", "4567", "another_key"]

Answer:

As is always true in programming, there are in fact multiple ways to accomplish this.

The most straightforward answer would be of the form:

hsh.keys.map(&:to_s).sort_by(&:length)

or:

hsh.keys.collect(&:to_s).sort_by { |key| key.length }

Alternatively, Ruby’s Enumerable mixin provides many methods to operate on collections. The key here is to turn the hash keys into a collection, convert them all to strings, then sort the array.

def key_sort hsh
	hsh.keys.collect(&:to_s).sort { |a, b| a.length <=> b.length }
end

An equivalent call of the collect method is done with the usual block syntax of:

collect { |x| x.to_s }

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