vtreat: prepare data

This article is on preparing data for modeling in R using vtreat. Suppose we wish to work with some data. Our example task is to train a classification model for credit approval using the ranger implementation of the random forests method. We will take our data from John Ross Quinlan's re-processed "credit approval" dataset hosted at Lichman, M. (2013). For convenience we have copied the data to our working directory here.