From: Robert Klemme <bob.news@...>
Date: 2005-11-28T21:52:29+09:00
Subject: Re: 2dim array/matrix

Wolfgang wrote:
> hello,
> 
> I'm quite new to programming as well to ruby. I want to store data in
> a 2 dimensional array. How can I do this?
> 
> A more detailed describtion of what I want to do:
> I have data from a digital elevation model. This is stored in a log
> txt file. I want to read it in and store it in an array or matrix.
> Because there are some error/gaps in the data I want to check for
> these values and calculate an average from the surrounding values. At
> the end all values should get written to an other txt file as x, y, z
> triples. The main problem for me to start is the 2dimensional
> storage. I know the needed size of the 2dim array/matrix
> (x-dim,y-dim). For getting the data in I was thinking of something
> like: dem[xi][yi]=value . 

The easiest to achieve that is

matrix = Array.new(dim_x) { Array.new(dim_y) }

There are also some matrix classes on the RAA
http://raa.ruby-lang.org/search.rhtml?search=matrix

For storage you can use CSV implementations or cook your own:

File.open("matrix.csv", "w") do |io|
  matrix.each_with_index do |yvalues, xidx|
    yvalues.each_with_index do |val, yidx|
      io.print xidx,yidx,val,"\n"
    end
  end
end

etc.

HTH

Kind regards

    robert