Dear all, Have tried using random forest for classfication and this is the code i wrote exactly: trial.rf<-randomForest(Type ~., data=trial) where Type is a column and determines the type and the trial is the data matrix. I keep getting this error: Error in eval (exprs, envir, enclos): object '117_at' not found. Where 117_at is a name of the first column. I tried removing this column but it gave me the same error for the next column. Any help? Regards,salwa [[alternative HTML version deleted]]

On 03/05/2012 09:43 AM, Salwa Eid wrote: > > > > > Dear all, Have tried using random forest for classfication and this is the code i wrote exactly: trial.rf<-randomForest(Type ~., data=trial) where Type is a column and determines the type and the trial is the data matrix. I keep getting this error: Error in eval (exprs, envir, enclos): object '117_at' not found. Where 117_at is a name of the first column. I tried removing this column but it gave me the same error for the next column. Any help? Regards,salwa > [[alternative HTML version deleted]] > It's usually better to post a complete example, sometimes with artificial data that still reproduces the error: > m = matrix(runif(100), nrow=20, dimnames=list(NULL, 1:5)) > randomForest(`1`~., data=m) Error in eval(expr, envir, enclos) : object '2' not found Knowing that symbols starting with digits need to be treated specially to be 'legal' (from section 1.8 of RShowDoc("R-intro")), and guessing that randomForest is doing something to associate the data with the formula, I tried > colnames(m) = paste("x", colnames(m), sep="") > randomForest(x1~., data=m) Call: randomForest(formula = x1 ~ ., data = m) Type of random forest: regression Number of trees: 500 No. of variables tried at each split: 1 Mean of squared residuals: 0.0941123 % Var explained: -41.17 randomForest documentation says that 'data' should be a data.frame, so perhaps I should have df = as.data.frame(m) randomForest(x1~., data=df) Martin > _______________________________________________ > Bioconductor mailing list > Bioconductor at r-project.org > https://stat.ethz.ch/mailman/listinfo/bioconductor > Search the archives: http://news.gmane.org/gmane.science.biology.informatics.conductor -- Computational Biology Fred Hutchinson Cancer Research Center 1100 Fairview Ave. N. PO Box 19024 Seattle, WA 98109 Location: M1-B861 Telephone: 206 667-2793