HDDT have been proposed to work well with imbalanced data [1].
The R file contains functions to create Hellinger distance decision tree (HDDT) given training data. It also provides a function to use a learned decision tree to predict new data.
I am currently using simple lists to store the tree. There are currently no functions to visualize the tree.
I will be happy to get feedback and make improvements, or even better if you have implemented improvements :)
[1] David A. Cieslak , Nitesh V. Chawla , Learning Decision Trees for Unbalanced Data, In European Conference on Machine Learning 2008.