[R] help with the usage of "randomForest"

[Hui Han]

Dear all,

Can anybody give me some hint on the following error msg I got with using 
randomForest?

I have two-class classification problem. The data file "sample" is:
----------------------------------------------------------
 udomain.edu udomain.hcs hpclass
1 1.0000 1 not
2 NA 2 not
3 NA 0.8 not
4 NA 0.2 hp
5 NA 0.9 hp
------------------------------------------------------------
The steps I called the function are:
(1) Read data
hp <- read.table("sample")
(2) Call randomForest
hp.rf <- randomForest(hpclass ~., yy, data=hp, importance=TRUE, 
proximity=TRUE)

But the error msg I got is:
Error in randomForest.default(m, y, ...) :
        Need at least two classes to do classification.


I learned the usage of randomForest from:
http://www.maths.lth.se/help/R/.R/library/randomForest/html/randomForest.html

Thanks a lot for any of your comments in advance!


Hui Han
Department of Computer Science and Engineering,
The Pennsylvania State University 
University Park, PA,16802
email: hhan at cse.psu.edu
homepage: http://www.cse.psu.edu/~hhan