The Pied Pipes The Pied Pipes - 2 months ago 10
Ruby Question

Padding printed output of tabular data

I know this is probably dead simple, but I've got some data such as this in one file:

Artichoke

Green Globe, Imperial Star, Violetto

24" deep

Beans, Lima

Bush Baby, Bush Lima, Fordhook, Fordhook 242

12" wide x 8-10" deep


that I'd like to be able to format into a nice TSV type of table, to look something like this:

Name | Varieties | Container Data
----------|------------- |-------
some data here nicely padded with even spacing and right aligned text

Answer

This is a reasonably full example that assumes the following

  • Your list of products is contained in a file called veg.txt
  • Your data is arranged across three lines per record with the fields on consecutive lines

I am a bit of a noob to rails so there are undoubtedly better and more elegant ways to do this

#!/usr/bin/ruby

class Vegetable

  @@max_name ||= 0  
  @@max_variety ||= 0  
  @@max_container ||= 0  

  attr_reader :name, :variety, :container

  def initialize(name, variety, container)
    @name = name
    @variety = variety
    @container = container  

    @@max_name = set_max(@name.length, @@max_name)  
    @@max_variety = set_max(@variety.length, @@max_variety)  
    @@max_container = set_max(@container.length, @@max_container)
  end

  def set_max(current, max)
    current > max ? current : max
  end

  def self.max_name  
    @@max_name  
  end  

  def self.max_variety  
    @@max_variety  
  end  

  def self.max_container()  
    @@max_container  
  end  

end

    products = []


    File.open("veg.txt") do | file|

      while name = file.gets
        name = name.strip
        variety = file.gets.to_s.strip
        container = file.gets.to_s.strip
        veg = Vegetable.new(name, variety, container)
        products << veg
      end
    end

    format="%#{Vegetable.max_name}s\t%#{Vegetable.max_variety}s\t%#{Vegetable.max_container}s\n"
    printf(format, "Name", "Variety", "Container")
    printf(format, "----", "-------", "---------")
    products.each do |p|
        printf(format, p.name, p.variety, p.container)
    end

The following sample file

Artichoke
Green Globe, Imperial Star, Violetto
24" deep
Beans, Lima
Bush Baby, Bush Lima, Fordhook, Fordhook 242
12" wide x 8-10" deep
Potatoes
King Edward, Desiree, Jersey Royal
36" wide x 8-10" deep

Produced the following output

       Name                                      Variety	            Container
       ----                                      -------	            ---------
  Artichoke         Green Globe, Imperial Star, Violetto	             24" deep
Beans, Lima Bush Baby, Bush Lima, Fordhook, Fordhook 242	12" wide x 8-10" deep
   Potatoes           King Edward, Desiree, Jersey Royal	36" wide x 8-10" deep