Padding printed output of tabular data - arrays

Question

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 1

Try String#rjust(width):
"hello".rjust(20) #=> " hello"

Answer 2

I wrote a gem to do exactly this: http://tableprintgem.com

Answer 3

No one has mentioned the "coolest" / most compact way -- using the % operator -- for example: "%10s %10s" % [1, 2]. Here is some code:
xs = [
["This code", "is", "indeed"],
["very", "compact", "and"],
["I hope you will", "find", "it helpful!"],
]
m = xs.map { |_| _.length }
xs.each { |_| _.each_with_index { |e, i| s = e.size; m[i] = s if s > m[i] } }
xs.each { |x| puts m.map { |_| "%#{_}s" }.join(" " * 5) % x }
Gives:
This code is indeed
very compact and
I hope you will find it helpful!
Here is the code made more readable:
max_lengths = xs.map { |_| _.length }
xs.each do |x|
x.each_with_index do |e, i|
s = e.size
max_lengths[i] = s if s > max_lengths[i]
end
end
xs.each do |x|
format = max_lengths.map { |_| "%#{_}s" }.join(" " * 5)
puts format % x
end

Answer 4

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

Answer 5

another gem: https://github.com/visionmedia/terminal-table
Terminal Table is a fast and simple, yet feature rich ASCII table generator written in Ruby.

Answer 6

I have a little function to print a 2D array as a table. Each row must have the same number of columns for this to work. It's also easy to tweak to your needs.
def print_table(table)
# Calculate widths
widths = []
table.each{|line|
c = 0
line.each{|col|
widths[c] = (widths[c] && widths[c] > col.length) ? widths[c] : col.length
c += 1
}
}
# Indent the last column left.
last = widths.pop()
format = widths.collect{|n| "%#{n}s"}.join(" ")
format += " %-#{last}s\n"
# Print each line.
table.each{|line|
printf format, *line
}
end

Answer 7

Kernel.sprintf should get you started.