From: dblack@...
Date: 2006-11-15T03:44:37+09:00
Subject: Re: Convert singel dimention array into grid

Hi --

On Wed, 15 Nov 2006, Giant Cranes wrote:

> Hi,
>
> I have been learning ruby for the past week and am completely hooked.
> Most of the code I am producing is elegant (ruby's credit), although I
> am having trouble elegantly converting a single dimension array with 16
> elements into a two-dimension grid [4x4].
>
> Here is what I have so far:
>
> @array = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16]
> @grid = Array.new
>
> i = 0
> index = 0
> 0.upto(3) do |i|
>  j = 0
>  0.upto(3) do |j|
>    @grid[i] = Array.new if j == 0
>    @grid[i][j] = @array[index]
>    index += 1
>    j += 1
>  end
>  i += 1
> end
>
> @grid

You can do:

   require 'enumerator'
   @array = [*1..16]   # :-)
   @grid = *@array.enum_slice(4)

Enumerators are, in my view, a bit less transparent than most Ruby
constructs, so this may look more cryptic than it's worth.  The basic
idea is that you're creating an object -- an Enumerator -- that has no
real data of its own but that represents, so to speak, the possibility
of an enumeration over @array, sliced up into groups of four.  Instead
of enumerating, I've converted it to a plain array with the *
operator.


David

-- 
                   David A. Black | dblack@rubypal.com
Author of "Ruby for Rails"   [1] | Ruby/Rails training & consultancy [3]
DABlog (DAB's Weblog)        [2] | Co-director, Ruby Central, Inc.   [4]
[1] http://www.manning.com/black | [3] http://www.rubypowerandlight.com
[2] http://dablog.rubypal.com    | [4] http://www.rubycentral.org