Hi, joseph wrote (15.2.2008): > Thanks. I have another question: > In the following data frame df, I want to replace all values in col1 > that are higher than 3 with NA. df= data.frame(col1=c(1:5, NA),col2= > c(2,NA,4:7)) My suggestion: x<-df$col1; x[ x>3 ]<-NA; df$col1<-x; rm(x) -Kimmo