From: Nuralanur@...
Date: 2006-07-23T01:21:44+09:00
Subject: Re: Showing part of an array....

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Rosina,
 
I'll explain this line:
 
colors[0..2].collect{ |color| color.name }.join(', ')


for an Array colors , say colors=['red','green','yellow'],
 
you can choose the first three entries by
colors[0..2],
then you map the elements of this Array (i.e., the Strings  using  the
collect command.
To be able to deal with them, you give the iterator a name, say  |color|.
But that's for the individual entries - you're trying to puit together a  
String
consisting of all the elements of color[0..2] ...
 
color.name only makes sense if you had defined it as a function.
Then you can map the entire Array to another Array and show
only the first so-and-so many of them. The following code translates
some color names into French. (I am not using the most compact
syntax Ruby is capable of below, since I want to keep things
easily understandable):
 
class String
  def name
        if self=='red'
          return  'rouge'
        end
 
if self=='blue'
          return  'bleu'
        end
        if self=='green'
          return  'vert'
        end
        if self=='white'
          return  'blanc'
        end
        if self=='yellow'
          return  'jaune'
         end
return 'unknown  color'   # Computer doesn't know so much French
    end
end
 
Best regards,
 
Axel 

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