3

How can i represent a 2d array in a table format in the terminal, where it lines up the columns properly just like a table?

so it looks like so:

         1       2       3          4          5
   1 [ Infinity | 40 | 45       | Infinity | Infinity ]
   2 [ Infinity | 20 | 50       | 14       | 20 ]
   3 [ Infinity | 30 | 40       | Infinity | 40 ]
   4 [ Infinity | 28 | Infinity | 6        | 6 ]
   5 [ Infinity | 40 | 80       | 12       | 0 ]

instead of:

[ Infinity,40,45,Infinity,Infinity ]
[ Infinity,20,50,14,20 ]
[ Infinity,30,40,Infinity,40 ]
[ Infinity,28,Infinity,6,6 ]
[ Infinity,40,80,12,0 ]
Improve this question
1
  • you, my new friend, asked an amazing question! Commented Oct 14, 2012 at 5:54

4 Answers 4

Reset to default
1 
a = [[Infinity, 40, 45, Infinity, Infinity],
    [Infinity, 20, 50, 14, 20 ],
    [Infinity, 30, 40, Infinity, 40 ],
    [Infinity, 28, Infinity, 6, 6 ],
    [Infinity, 40, 80, 12, 0 ]]

Step by Step Explanation

You first need to acheive the column width. col_width below is an array that gives the width for each column.

col_width = a.transpose.map{|col| col.map{|cell| cell.to_s.length}.max}

Then, this will give you the main part of the table:

a.each{|row| puts '['+
 row.zip(col_width).map{|cell, w| cell.to_s.ljust(w)}.join(' | ')+']'}

To give the labels, do the following.

puts ' '*(a.length.to_s.length + 2)+
    (1..a.length).zip(col_width).map{|i, w| i.to_s.center(w)}.join('   ')

a.each_with_index{|row, i| puts "#{i+1} ["+
    row.zip(col_width).map{|cell, w| cell.to_s.ljust(w)}.join(' | ')+
    ']'
}

All in One This is for ruby1.9. Small modification shall make it work on ruby 1.8.

a
.transpose
.unshift((1..a.length).to_a)   # inserts column labels #
.map.with_index{|col, i|
    col.unshift(i.zero?? nil : i)   # inserts row labels #
    w = col.map{|cell| cell.to_s.length}.max   # w = "column width" #
    col.map.with_index{|cell, i|
         i.zero?? cell.to_s.center(w) : cell.to_s.ljust(w)}   # alligns the column #
}
.transpose
.each{|row| puts "[#{row.join(' | ')}]"}
Improve this answer
Sign up to request clarification or add additional context in comments.

2 Comments

Hi, thanks for the answer but its giving me a: undefined method `with_index' for [0, 20, 5, Infinity, Infinity]:Array (NoMethodError) im using ruby 1.8.*
Thank you veru much that worked great, just one question though, how could I put lables for the rows and columns? just like in the example in the question.
1

Try this:

a = [['a', 'b', 'c'], ['d', 'e', 'f']]
puts a.map{|e| "[ %s ]" % e.join(",")}.join("\n")

Edit:

Extended the answer based on additional request.

a = [
  [ "Infinity",40,45,"Infinity","Infinity" ],
  [ "Infinity",20,50,14,20 ],
  [ "Infinity",30,40,"Infinity",40 ],
  [ "Infinity",28,"Infinity",6,6 ],
  [ "Infinity",40,80,12,0 ]
]

def print_2d_array(a, cs=12)
  report = []   
  report << " " * 5 + a[0].enum_for(:each_with_index).map { |e, i|
    "%#{cs}s" % [i+1, " "]}.join("   ")
  report << a.enum_for(:each_with_index).map { |ia, i|
    "%2i [ %s ]" % [i+1, ia.map{|e| "%#{cs}s" % e}.join(" | ") ] }
  puts report.join("\n")
end

Output

Now calling print_2d_array(a) produces the result below. You can increase the column size based on your requirement.

                1              2              3              4              5
 1 [     Infinity |           40 |           45 |     Infinity |     Infinity ]
 2 [     Infinity |           20 |           50 |           14 |           20 ]
 3 [     Infinity |           30 |           40 |     Infinity |           40 ]
 4 [     Infinity |           28 |     Infinity |            6 |            6 ]
 5 [     Infinity |           40 |           80 |           12 |            0 ]
Improve this answer

1 Comment

Hi, is there a way to make it in to an actual table? i updated my question for an example. Thank You
0 
a = [['a', 'b', 'c'], ['d', 'e', 'f']]
a.each {|e| puts "#{e.join ", "}\n"}

Not the simplest way maybe, but works

a, b, c
d, e, f
Improve this answer

1 Comment

Hi, is there a way to make it in to an actual table? i updated my question for an example. Thank You
0

Well, if I was doing it, I would go:

require 'pp'
pp my_2d_array

But if this is homework, I suppose that won't work. Perhaps:

puts a.inject("") { |m, e| m << e.join(' ') << "\n" }
Improve this answer

5 Comments

Never heard of prettyprint before, but it seems to produce the same result for arrays as normal p.
@Nikita, you just haven't tried a complex example. It will do something much better than p with, say, pp([t = %w{how now brown cow}, t, t])
This dosnt seem to work for 2d array's, i got irb(main):001:0> require 'pp' => true irb(main):002:0> d = [[2, 3, 4], [2, 6, 9]] => [[2, 3, 4], [2, 6, 9]] irb(main):003:0> pp d [[2, 3, 4], [2, 6, 9]] => nil irb(main):004:0> d => [[2, 3, 4], [2, 6, 9]] irb(main):005:0>
@Mo, that's not the way the #pretty_print API works, its data argument must be a single parameter, if you give it a second or third, it will use them as the output IO object and the page width. The API is documented in the Ruby Standard Library.
@DigitalRoss Ok, I get the trick. It prints two-row arrays in one line, but for 3 or more rows it puts each into a separate line. Tricks, tricks, tricks.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.