Ruby ASCII table

ruby-ascii-table.rb

# [
#   {
#     'foo' => 'bar',
#     'baz' => 'qux',
#   },
#   {
#     'foo' => true,
#     'baz' => 1,
#   },
# ]
def print_table(data)
  # conver to 2D array
  table = [data.first.keys] + data.map(&:values)

  widths = []
  table.each do |line|
    c = 0
    line.each do |col|
      col = col.to_s
      widths[c] = (widths[c] && widths[c] > col.length) ? widths[c] : col.length
      c += 1
    end
  end

  # header separator
  table.insert(1, widths.map { |n| '-' * n })

  format = widths.collect { |n| "%-#{n}s"}.join(" | ")
  table.each_with_index do |line, i|
    printf "| #{format} |\n", *line
  end
end