Visualizing confusion matrices

I always wanted to be able to visualize large confusion matrices as a heatmap. Making it easier to visualize where misclassifications hot spots are. Hence I started another plugin project for the Weka Explorer

It offers, at the moment, the following visualizations:

  • text – slightly enhanced default text representation, can be saved as text file or printed
  • table – representing the matrix in a JTable, can be saved as CSV file or printed
  • heatmap – counts in the matrix get represented using colors chosen from a gradient generated from two colors, can be saved as image file

Here is an example of the heatmap visualization, using the matrix generated by J48 on the UCI dataset optdigits: