fancyRpartPlot: A wrapper for plotting rpart trees using prp

# NOT RUN {
## Use rpart to build a decision tree.

# }
# NOT RUN {
library(rpart)

## Set up the data for modelling.

set.seed(42)
ds     <- weather
target <- "RainTomorrow"
risk   <- "RISK_MM"
ignore <- c("Date", "Location", risk)
vars   <- setdiff(names(ds), ignore)
nobs   <- nrow(ds)
form   <- formula(paste(target, "~ ."))
train  <- sample(nobs, 0.7*nobs)
test   <- setdiff(seq_len(nobs), train)
actual <- ds[test, target]
risks  <- ds[test, risk]

# Fit the model.

fit <- rpart(form, data=ds[train, vars])

## Plot the model.

fancyRpartPlot(fit)

## Choose different colours.

fancyRpartPlot(fit, palettes=c("Greys", "Oranges"))

## Add a main title to the plot.

fancyRpartPlot(fit, main=target) 

# }