Tagged: basis

A Story about Data, Part 2: Abandoning the notion of normality

Continuing on with my work, I was just about to conclude the non-normal data of the distribution. However, I remembered reading about different transformations that can be applied to data to make it more normal. Are any such transformations likely to have any effect on the normality (or the lack thereof) of the score data?
I’d read about the Box-Cox family of transformations: essentially proceeding through powers and their inverses, in the quest to improve normality. I decided to try it, using the Jarque-Bera statistic as a measure of the normality of the data.
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Installing the Basis gem (updated for v0.5.1+)

You can use Ruby-Processing in two ways.

    Use the jruby-complete.jar that Ruby-Processing ships, the Gems-in-a-Jar approach. In this mode, all gems you install will be packaged as part of the JAR.
    Using the JRuby already installed on your system.

If you’re following the first approach, first head to the location where the jruby-complete.jar is located, for Ruby-Processing. There, do this:

java -jar jruby-complete.jar -S gem install basis-processing --user-install

Alternatively, if you’re using a conventional JRuby installation, do this:

sudo jruby -S gem install basis-processing

A guide to using Basis (updated for v0.6.0+)

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.
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Basis: Plotting arbitrary coordinate systems in Ruby-Processing

One of the first things I realised while working on visualisations in Processing is that a lot of the work required in setting up coordinate systems and plotting them is somewhat of a chore. Specifically, for things like parallel coordinates, multiple axes, each with its own scaling, I initially ended up with some pretty ugly custom code for each case. I did look around in the Libraries section of the Processing website, but didn’t find anything specific to manipulating and plotting coordinate axes.
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