R: Subset: Using whole dataframe except one column

I'd like to exclude one single column from a operation on a dataframe. Of course I could just replicate the dataframe without the column that I want to exclude, but this seems to be a workaround. There must be an easier way to subset I think. So this example code should show what I am up to. ``` df<-data.frame(a=c(1:5),b=c(6:10),c=c(11:15)) # First subset: operate on a single column mean(df[,1]) [1] 3 # Second subset: with a set of choosen columns colMeans(df[,c(1,3)]) a c 3 13 # third subset: exclude column b from the operation (expected Output should be like the second subset) colMeans(df[,!=2]) Error: unexpected '!=' in "colMeans(df[,!=" ``` Any help would be very appreciated.