How to sort an array in Ruby to a particular order?

Question

I want to sort an array in particular order given in another array.

EX: consider an array

a=[\"one\", \"two\", \"three\"]
b=[\"two\", \"one\", \"thr         


        

Answer 1

Assuming a is to be sorted with respect to order of elements in b

sorted_a = 
a.sort do |e1, e2|
  b.index(e1) <=> b.index(e2)
end

I normally use this to sort error messages in ActiveRecord in the order of appearance of fields on the form.