From: Josh Cheek <josh.cheek@...>
Date: 2010-03-19T13:12:07+09:00
Subject: Re: problem making an array of arrays (of arrays)

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On Thu, Mar 18, 2010 at 6:26 PM, Cec Tre <cecil.treadwell@gmail.com> wrote:

> Hey, bit of a ruby noob here :)
>
> First, hello ruby-forum community.
>
> So, here is my problem. I want to create a 5x5 grid, however, each of
> the 'cells' in the grid should be able to hold a variety of values.
>
> Firstly, I started off with this:
>
>    @row_1 = ['x','x','x','x','x']
>    @row_2 = ['x','x','x','x','x']
>    @row_3 = ['x','x','x','x','x']
>    @row_4 = ['x','x','x','x','x']
>    @row_5 = ['x','x','x','x','x']
>    @grid = [@row_1,@row_2,@row_3,@row_4,@row_5]
>
> So, obviously this creates a 5x5 grid, in which each of the 'cells' or
> @row_1..5[1..5] == 'x'.
>
> I used to just alter the string value in each cell by using:
>
>    @grid[y][x] = 'new string'
>
> But, I ultimately want each cell to be an array.. So that I can push and
> pop their values as they change, and then the grid will always display
> the last value in the array, by using:
>
>    @row_1 = [array.last,array1.last,array2.last,array3.last]
>    #etc etc etc...
>
> My problem then is, that I have a different variable name for each of
> the five points in each of the five rows.
>
> So, the solution I really want is:
>
> Is it possible to have a variable called, say... cellxx ... Then, some
> piece of code that alters the xx part of the actual variable name
> itself?
>
> Because, I'm going about implementing cell00, cell01, cell02, cell03 etc
> etc each as an array and my code is getting messy.
>
> Please is there an (easier) way, to do what I want?
>
> Sorry for the length of this, you can tell i'm new to ruby :) Thanks!
> --
> Posted via http://www.ruby-forum.com/.
>
>

Personally, I think I would opt for nested classes in this case, but if I
understand your problem correctly, then this should do what you are asking.


# the 2d array of elements that are arrays
# each currently containing it's yx location as a string
array = [[["00"], ["01"], ["02"], ["03"], ["04"]],
         [["10"], ["11"], ["12"], ["13"], ["14"]],
         [["20"], ["21"], ["22"], ["23"], ["24"]],
         [["30"], ["31"], ["32"], ["33"], ["34"]],
         [["40"], ["41"], ["42"], ["43"], ["44"]]]

# go through the array and set variables to reference the individual cells
array.each_with_index do |row,y|
  row.each_with_index do |element,x|
    instance_variable_set "@array#{y}#{x}" , element
  end
end

# show that we can access it as you describe
@array00 << 'a'
@array01 << 'b'
@array11 << 'c'
@array22 << 'd'
@array33 << 'e'
@array43 << 'f'
@array44 << 'g'

# format the output so that it is easier to see what we did
puts '['
array.each do |row|
  print '  [ '
  row.each do |col|
    printf '%-12s , ' , col.inspect
  end
  puts ' ]'
end
puts ']'

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