From: Rob Biedenharn <Rob@...>
Date: 2009-12-08T22:32:57+09:00
Subject: Re: indent strings(make them lined up)

On Dec 8, 2009, at 5:11 AM, Justin Collins wrote:
> Jon Kim wrote:
>> Hi,
>>
>> I am newbie in Ruby. I have a question about indenting string.
>>
>> there is strings like below:
>>
>> www.google.com => 123.123.123.12
>> www.ibm.com => 123.112.123.12
>> www.iowahawkeyes => 123.123.112.12
>>
>> i want to make above like next
>>
>> www.google.com     => 123.123.123.12
>> www.ibm.com        => 123.112.123.12
>> www.iowahawkeyes   => 123.123.112.12
>>
>>
>> original code was
>>
>> puts (dns + " => " + ip)
>>
>> I tried next code
>>
>> puts (dns + "  "*(20 - dns.length) + " = > " + ip)
>>
>> but it did not work well. please teach me how to do it.
>>
>
> You could do
>
> puts "#{dns.ljust(20)} => #{ip}"
>
> -Justin

OK, I'm going to go out on a limb and presume that you obtain the  
successive dns and ip values from some sort of data structure. I'm  
going to further assume a hash since you're using the association  
syntax in your output string, but feel free to generalize the parts of  
this code that handle that iteration.

irb> my_data = {
?>         'www.google.com' => '216.68.119.70',
?>         'www.ibm.com' => '129.42.60.216',
?>         'www.iowahawkeyes.com' => '199.108.163.135',
?>       }
=> {"www.google.com"=>"216.68.119.70", "www.ibm.com"=>"129.42.60.216",  
"www.iowahawkeyes.com"=>"199.108.163.135"}
irb> width = my_data.keys.inject(0) {|wmax,dns| [dns.length, wmax].max }
=> 20
irb> my_data.each do |dns,ip|
?>         puts "%-*s => %s"%[width, dns, ip]
irb>   end
www.google.com       => 216.68.119.70
www.ibm.com          => 129.42.60.216
www.iowahawkeyes.com => 199.108.163.135
=> {"www.google.com"=>"216.68.119.70", "www.ibm.com"=>"129.42.60.216",  
"www.iowahawkeyes.com"=>"199.108.163.135"}
irb>
?>     my_data['www.letmegooglethatforyou.com'] = '209.20.88.2'
=> "209.20.88.2"
irb>
?>     width = my_data.keys.inject(0) {|wmax,dns| [dns.length,  
wmax].max }
=> 29
irb> my_data.each do |dns,ip|
?>         puts "#{dns.ljust(width)} => #{ip}"
irb>   end
www.google.com                => 216.68.119.70
www.ibm.com                   => 129.42.60.216
www.letmegooglethatforyou.com => 209.20.88.2
www.iowahawkeyes.com          => 199.108.163.135
=> {"www.google.com"=>"216.68.119.70", "www.ibm.com"=>"129.42.60.216",  
"www.letmegooglethatforyou.com"=>"209.20.88.2",  
"www.iowahawkeyes.com"=>"199.108.163.135"}

You could also put a limit on the width of the column so that one long  
value doesn't "win" or analyze the widths for some other property  
(like rounding up to a multiple of 4 or something).

-Rob

Rob Biedenharn		http://agileconsultingllc.com
Rob@AgileConsultingLLC.com