Transpose hash to rows and expand to match max element count.

transpose_rows.rb

def transpose_rows(hash)
  separator = ' '
  rows = []
  rows << hash.keys.join(separator) # header

  all = []
  max_elements = 0
  hash.each do |_, arr|
    all << arr
    max_elements = arr.length if arr.length > max_elements
  end

  all.map! { |arr| expand(arr, max_elements) }
  rest = all.slice(1, all.length)
  all.first.zip(*rest).each { |row| rows << row.join(separator) }
  rows
end

def expand(arr, max_elements, default = 0)
  size = max_elements - arr.length
  arr.concat(Array.new(size, default.to_i))
end


data = {
  a: %w(a b c),
  b: [1, 2, 3, 4, 5],
  c: [9, 8, 7, 6, 44, 33, 22]
}

transpose_rows(data)

#[
#    [0] "a b c",
#    [1] "a 1 9",
#    [2] "b 2 8",
#    [3] "c 3 7",
#    [4] "0 4 6",
#    [5] "0 5 44",
#    [6] "0 0 33",
#    [7] "0 0 22"
#]