Ruby function to display an array of strings as columns on a text terminal

format_as_columns.rb

#!/usr/bin/env ruby
#
# Ruby function to display an array of strings
# as columns on a text terminal.
#
# Author: Nicholas Humfrey
# License: https://unlicense.org/
#

require 'io/console'

def format_as_columns(strings, column_count, column_width = nil)
  per_column = (strings.count.to_f / column_count).ceil

  if column_width.nil?
    height, width = IO.console.winsize
    column_width = (width.to_f / column_count).floor
  end

  result = []
  (0...per_column).each do |r|
    row = ''
    (0...column_count).each do |c|
      index = (c * per_column) + r
      if strings[index].nil?
        item = ''
      else
        item = strings[index]
      end
      row += item.ljust(column_width)
    end
    result << row
  end

  return result
end

strings = <<~END
  1: One
  2: Two
  3: Three
  4: Four
  5: Five
  6: Six
  7: Seven
  8: Eight
  9: Nine
  10: Ten
  11: Eleven
  12: Twelve
  13: Thirteen
  14: Fourteen
  15: Fifthteen
  16: Sixteen
  17: Seventeen
  18: Eighteen
  19: Nineteen
  20: Twenty
END
  .split("\n")

puts format_as_columns(strings, 3).join("\n")



# Result:
#
# 1: One                    8: Eight                  15: Fifthteen             
# 2: Two                    9: Nine                   16: Sixteen               
# 3: Three                  10: Ten                   17: Seventeen             
# 4: Four                   11: Eleven                18: Eighteen              
# 5: Five                   12: Twelve                19: Nineteen              
# 6: Six                    13: Thirteen              20: Twenty                
# 7: Seven                  14: Fourteen