HI, Please check this link (http://r.789695.n4.nabble.com/Remove-levels-td4669441.html). It was posted today. df1<-subset(df, Trt!="blank") df2<- df1 df1$Trt<- factor(df1$Trt) levels(df1$Trt) #[1] "Trt1" "Trt2"
#or df2$Trt<-droplevels(df2$Trt) levels(df2$Trt) #[1] "Trt1" "Trt2" A.K. Hey guys I am new and a beginner. So far I searched the forum for an answer. Did not found anything. Here is the Problem. I have a data.frame Time <- c(1,2,1,1,2,2,3,3) Trt <- factor(c("blank", "blank", "Trt1", "Trt1", "Trt1", "Trt2", "Trt2", "Trt2")) OD600 <- c(0.1,0.2,0.18,0.3,0.16,0.21,0.25,0.16) df <- data.frame(Time,Trt,OD600) No I apply: df<-subset(df, Trt!="blank") So the data.frame has no rows matching Trt=blank" anymore (looking at the data set). So far so good. However if I type in: levels(df$Trt) I get the result: [1] "blank" "Trt1" "Trt2" Somehow it is still somwhere. How can I remove the blank from the data.frame definitely? Thanks for the help. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.