# 2dim array/matrix **URL:** \ **Category:** ruby-talk\ **Created:** [28 November 2005 12:22 UTC](https://rubytalk.org/t/2dim-array-matrix/22818 "2005-11-28T12:22:29Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Wolfgang](https://avatars.discourse-cdn.com/v4/letter/w/54ee81/32.png) [@Wolfgang](https://rubytalk.org/u/Wolfgang)\ **Post date:** [28 November 2005 12:22 UTC](https://rubytalk.org/t/2dim-array-matrix/22818/1 "2005-11-28T12:22:29Z")
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 . Kind regards Wolfgang ---
**Author:** ![Robert](https://avatars.discourse-cdn.com/v4/letter/r/e95f7d/32.png) [@Robert](https://rubytalk.org/u/Robert)\ **Post date:** [28 November 2005 12:52 UTC](https://rubytalk.org/t/2dim-array-matrix/22818/2 "2005-11-28T12:52:29Z")
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](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 ---
**Author:** ![Tim\_Hunter](https://avatars.discourse-cdn.com/v4/letter/t/7feea3/32.png) [@Tim\_Hunter](https://rubytalk.org/u/Tim_Hunter)\ **Post date:** [28 November 2005 13:02 UTC](https://rubytalk.org/t/2dim-array-matrix/22818/3 "2005-11-28T13:02:58Z")
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 . > > Kind regards > > Wolfgang Ruby has a Matrix class in the standard library. Check out "matrix" in the [http://www.ruby-doc.org/stdlib/\](http://www.ruby-doc.org/stdlib/%5C). ---
**Author:** ![Wolfgang](https://avatars.discourse-cdn.com/v4/letter/w/54ee81/32.png) [@Wolfgang](https://rubytalk.org/u/Wolfgang)\ **Post date:** [28 November 2005 13:42 UTC](https://rubytalk.org/t/2dim-array-matrix/22818/4 "2005-11-28T13:42:29Z")
Thanks for the answers, I think I will use for the beginning this solution:   mx = Array.new(dim\_x) { Array.new(dim\_y) } for the matrix class: I don't understand how I can set in a matrix single values:   require "matrix"   m=Matrix[[25, 93], [-1, 66] ]   puts m.[](1,1) this works but when I try:   m.[](1,1)=123   puts m I only get an error. Wolfgang ---
**Author:** ![Brian\_Schroder1](https://avatars.discourse-cdn.com/v4/letter/b/2bfe46/32.png) [@Brian\_Schroder1](https://rubytalk.org/u/Brian_Schroder1)\ **Post date:** [28 November 2005 13:49 UTC](https://rubytalk.org/t/2dim-array-matrix/22818/5 "2005-11-28T13:49:59Z")
Try these: puts m[1,1] m[1,1] = 123 pits m[1,1] brian > **ยทยทยท** > > On 28/11/05, Wolfgang \ wrote: > > > Thanks for the answers, > > > > I think I will use for the beginning this solution: > >         mx = Array.new(dim\_x) { Array.new(dim\_y) } > > > > for the matrix class: > > I don't understand how I can set in a matrix single values: > >         require "matrix" > >         m=Matrix[[25, 93], [-1, 66] ] > >         puts m.(1,1) > > this works but when I try: > >         m.(1,1)=123 > >         puts m > > I only get an error. > > > > Wolfgang > > -- > [http://ruby.brian-schroeder.de/](http://ruby.brian-schroeder.de/) > > Stringed instrument chords: [http://chordlist.brian-schroeder.de/](http://chordlist.brian-schroeder.de/) ---
**Author:** ![Robert](https://avatars.discourse-cdn.com/v4/letter/r/e95f7d/32.png) [@Robert](https://rubytalk.org/u/Robert)\ **Post date:** [28 November 2005 13:52 UTC](https://rubytalk.org/t/2dim-array-matrix/22818/6 "2005-11-28T13:52:29Z")
Wolfgang wrote: > Thanks for the answers, > > I think I will use for the beginning this solution: > mx = Array.new(dim\_x) { Array.new(dim\_y) } > > for the matrix class: > I don't understand how I can set in a matrix single values: > require "matrix" > m=Matrix[[25, 93], [-1, 66] ] > puts m.(1,1) > this works but when I try: > m.(1,1)=123 > puts m > I only get an error. You probably misread the documentation. Did you try m[1,1] m[1,1] = 123 ? Kind regards     robert ---
**Author:** ![ts1](https://avatars.discourse-cdn.com/v4/letter/t/a8b319/32.png) [@ts1](https://rubytalk.org/u/ts1)\ **Post date:** [28 November 2005 14:00 UTC](https://rubytalk.org/t/2dim-array-matrix/22818/7 "2005-11-28T14:00:46Z")
> m[1,1] = 123 Try it ๐Ÿ™‚ moulon% ruby -rmatrix -e 'm = Matrix[[25, 93], [-1, 66]]; m[1, 1] = 123' -e:1: undefined method `=' for Matrix[[25, 93], [-1, 66]]:Matrix (NoMethodError) moulon% Guy Decoux ---
**Author:** ![Robert](https://avatars.discourse-cdn.com/v4/letter/r/e95f7d/32.png) [@Robert](https://rubytalk.org/u/Robert)\ **Post date:** [28 November 2005 15:02 UTC](https://rubytalk.org/t/2dim-array-matrix/22818/8 "2005-11-28T15:02:36Z")
ts wrote: > > m[1,1] = 123 > > Try it ๐Ÿ™‚ > > moulon% ruby -rmatrix -e 'm = Matrix[[25, 93], [-1, 66]]; m[1, 1] = > 123' -e:1: undefined method `=' for Matrix[[25, 93], [-1, > 66]]:Matrix (NoMethodError) moulon% "cool" ๐Ÿ™‚     robert