Exercise: Calculating the array mode

mode.rb

# Write a method mode which takes an Array of numbers as its input and returns 
# an Array of the most frequent values.

# If there's only one most-frequent value, it returns a single-element Array.

# For example,

# mode([1,2,3,3])         # => [3]
# mode([4.5, 0, 0])       # => [0]
# mode([1.5, -1, 1, 1.5]) # => [1.5]
# mode([1,1,2,2])         # => [1,2]
# mode([1,2,3])           # => [1,2,3], because all occur with equal frequency

def mode(array)
  result = []
  ordered = array.sort
  new_array = ordered.sort_by { |var| (ordered.rindex(var)) - (ordered.index(var)) }
  array_last = new_array.last
  new_array.each do |var|
    if (ordered.rindex(var) - ordered.index(var)) == (ordered.rindex(array_last) - ordered.index(array_last))
      result.push(var)
    end
  end
  result.uniq
end