Equally distribute several array elements across single array. (Ruby)

array.rb

#!/usr/bin/env ruby
require 'pp'

a = []
a << [:a, :c, :e]
a << [:b, :f, :g, :h, :i, :j]
a << [:d]


# element coefficients
def get_coefficients array
  (1..array.size).map { |i| (i - 0.5) / array.size }
end



elements = []
coefficients = []
a.each do |e| 
  elements += e 
  coefficients += get_coefficients(e)
end


# Combine all the arrays with their sort index.
combined = elements.zip(coefficients)


# Extract the values from the original arrays in their new order
r = combined.sort_by { |zipped| zipped[1] }.map { |zipped| zipped[0] }

pp r
# [:b, :a, :f, :g, :d, :c, :h, :i, :e, :j]