This is a quick tour of Basis. Find the source for Basis on GitHub. Installing Basis is pretty simple; just grab it as a gem for your JRuby installation. Brief notes on the installation can be found here.
UPDATE: Starting from version 0.6.0, Basis allows you to specify axis labels. Additionally, you can specify arrays of points instead of plotting points one at a time. When you do this, you can also specify a corresponding legend string, which will show up in a legend guide. See below for more details.
UPDATE: Starting from version 0.5.9, you can turn grid lines on or off. Additionally, the matrix operations implementation has been ported to use the Matrix class in Ruby’s stdlib.
UPDATE: Starting from version 0.5.8, you can customise axis labels, draw arbitrary shapes/text/plot custom graphics at any point in your coordinate system. See below for more details.
UPDATE: With version 0.5.7, experimental support has been added for drawing objects which aren’t points. Interactions with such objects is currently not supported. Additional support for drawing markers/highlighting in custom bases is now in.
UPDATE: Starting from version 0.5.1, Basis has been ported to Ruby 1.9.2, because of the kd-tree library dependency. Currently, there are no plans of maintaining Basis compatibility with Ruby 1.8.x. As an aside, I personally recommend using RVM to manage the mess of Ruby/JRuby installations that you’re likely to have on your machine.
UPDATE: Basis has hit version 0.5.0 with experimental support for mouseover interactivity. More work is incoming, but the demo code below is up-to-date, for now. The code below should be the same as demo.rb on GitHub.