Ruby - pick randomly from an array

Question

I want to know if there is a much cleaner way of doing this. Basically, I want to pick a random element from an array of variable length. Normally, I would do it like this:

myArray = ["stuff", "widget", "ruby", "goodies", "java", "emerald", "etc" ]
item = myArray[rand(myarray.length)]

Is there something that is more readable / simpler to replace the second line? Or is that the best way to do it. I suppose you could do myArray.shuffle.first, but I only saw #shuffle a few minutes ago on SO, I haven't actually used it yet.

Thanks!

Answer 1

Try this

item = self[rand(self.length)]

Answer 2

Personally, I would prefer the method item = myArray.random_element. UPDATE: Before Ruby 1.8.7, you had to define the method yourself. See the answer for Marc-André Lafortune for a more modern view.

class Array
  def random_element
    self[rand(length)]
  end
end

Answer 3

Wasn't there sample/choice method?

Answer 4

Just use Array#sample:

[:foo, :bar].sample # => :foo, or :bar :-)

It is available in Ruby 1.9 (and upcoming 1.8.8), so if using an earlier version, require "backports". Note that in Ruby 1.8.7 it exists under the unfortunate name choice; it was renamed in later version so you shouldn't use it.