Gather values from an array of hashes

array-pluck.rb

class Array
  def pluck key
    map { |hash| hash[key] }
  end
end

[{:number => "1"}, {:number => "2"}, {:number => "3"}].pluck(:number)
# => ["1", "2", "3"]

Okay, but (slightly more realistically):

[{:odd => "1", :even => "2"}, {:odd => "3", :even => "4"}, {:odd => "5", :even => "6"}].pluck(:even)
# => ["2", "4", "6"]

Whereas:

[{:odd => "1", :even => "2"}, {:odd => "3", :even => "4"}, {:odd => "5", :even => "6"}].map(&:first).map(&:last)
# => ["1", "3", "5"]

Also, we need to be key-order agnostic, so map(&:second) isn't viable.