From: Joel VanderWerf <vjoel@...>
Date: 2009-08-04T14:33:15+09:00
Subject: Re: How to extract only needed attribute from an array

Thriving K. wrote:
> I have an object called Tags with id and name ==> [ tag.id , tag.name]
> 
> | [1 , aaa]   |
> 
> | [ 3 , bbb]  |
> 
> | [ 5 , ccc]  |
> 
> | [ 6 , dfd]  |
> 
> | [ 7 , waf]  |
> 
> | [ 11 , vee] |
> 
> There is an array with the list of tags , i just want to extract all
> tag.id
> as a new array, what is the easiest way to do

Is this how your array looks?

a = [
   [1 , :aaa],
   [ 3 , :bbb],
   [ 5 , :ccc],
   [ 6 , :dfd],
   [ 7 , :waf],
   [ 11 , :vee]
]

p a.transpose[0] # ==> [1, 3, 5, 6, 7, 11]

Or:

p a.map {|b| b[0]}

-- 
       vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407