We can use the ! operator inorder to make any TRUE FALSE or FALSE TRUE.
So consider a condition where, a categorical variable V1 in a data frame n can have values represented by the letters from A to Z. I want to create a subset m, which excludes some values, say, C, N and P.
m = subset(n, !(V1 %in% c('C','N',P'))) // opposite of %in%