目前自己写的版本

def sample_group(array, group_array = [2,3,4,5])
    group = []
    while array.size > 0
      rand = group_array.sample
      group << array.first(rand)
      array = array.drop(rand)
    end
    group
  end

测试数组：[1,2,3,4,5,6,7,8,9] 结果：

[[1, 2, 3, 4], [5, 6, 7, 8], [9]]
[[1, 2], [3, 4], [5, 6, 7, 8, 9]]
[[1, 2], [3, 4, 5], [6, 7, 8, 9]]