RockPaperScissors

LizardSpock

Print Nested Array Structures in Table Format

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Problem

Take an array of arrays and format it for displaying to the terminal or outputting to a text file.

Sample Data:

data = [[1,2,3,4,5],["Four","Five","Six"],["Seven","Eight","Nine","Ten"]]

Solution

The main issue I see is working out how wide to make each column. My solution is to iterate over the data keeping track of the maximum width found for each column.

Once we know how wide to make each column printing the table is just a matter of a second iteration over the data using ljust or rjust to align all the columns.

def print_table( data )
  #Clone/dup nested structure
  data = Marshal.load(Marshal.dump(data))
  #data = data_array.dup
  lengths = []

  data.each do |line| 
    line.each_with_index do |item, column| 
      length          = item.to_s.size
      lengths[column] = length if length > (lengths[column] ||= 0)
    end
  end

  data.each do |line| 
    line.each_with_index do |item, column|
      line[column] = item.to_s.rjust(4+lengths[column])
      print line[column]
    end
    puts
  end

  return data
end

The result:

data = [[1,2,3,4,5],["Four","Five","Six"],["Seven","Eight","Nine","Ten"]]
data = print_table( data )

=>        1        2       3      4    5    
=>     Four     Five     Six
=>    Seven    Eight    Nine    Ten

Alternative Solution

Use the terminal-table gem. Which creates nice ASCII tables.

#gem install terminal-table

require 'terminal-table'
data = [[1,2,3,4,5],["Four","Five","Six"],["Seven","Eight","Nine","Ten"]]
table = Terminal::Table.new :rows => data

puts table
+-------+-------+------+-----+---+
| 1     | 2     | 3    | 4   | 5 |
| Four  | Five  | Six  |
| Seven | Eight | Nine | Ten |
+-------+-------+------+-----+---+

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