[R-sig-eco] handling ca

[Griffith.Michael at epamail.epa.gov]

In trying to use randomForest, I got the following error message:

Error in data.matrix(x) : non-numeric data type in frame

Am I correct that this means that randomForest  has not be written in R
to handle categorical predictor variables?  Is there a way around this?
I am working with two categorical variables (out of 4 predictor
variables) with more than 2 levels that do not have any particular order
to them.  The instructions for the original random forest program by
Brieman indicates that it handles categorical predictor variables, so I
am surprised that the R version does not.

Michael

Michael B. Griffith, Ph.D.
Research Ecologist

USEPA, NCEA (MS A-110)
26 W. Martin Luther King Dr.
Cincinnati, OH  45268

telephone:  513 569-7034
e-mail:  griffith.michael at epa.gov