将数组的元素与该数组中的其他元素匹配

Question

I have an array containing several students. I want them to cross-grade one another randomly, ie each student will grade someone and will be graded by someone else (these two people may or may not be the same person).

Here is my close to working solution. One big problem with this code is that the last person may have to grade himself if everyone else has been matched.

I am very interested in a working and more elegant solution.

def randomize(student_array)
  graders = student_array.dup
  gradees = student_array.dup
  result = {}
  graders.each do |grader|
    gradee = grader
    while gradee == grader
      gradee = gradees.sample
    end
    result[grader] = gradee
    gradees.delete_at(gradees.index(gradee))
  end
  return result
end

Answer 1

If you don't have to pick up one from all possibilities but pick up a random case from limited cases, then it is easy. For example, the following will give a match:

student_array = %i[a b c d e]
a = student_array.shuffle
[a, a.rotate(1)].transpose.to_h
# => {:b => :e, :e => :d, :d => :a, :a => :c, :c => :b}