R help - Mar 2011 - Re transaction list transformation to use rpart.

> However the as.data.frame(a) transforms the matrix into a numeric
> data.frame so when I implement the rpart algorithm it automatically
> returns a regression classification tree.
  Look at help(rpart).  The program uses the type of the y variable to
GUESS at what you want for the "method" argument.  It often guesses
wrong. Simply add 
   method="class"
as an argument to your call.

Terry Therneau