Question

I have a dataframe m and I want to remove all the rows where the f_name column has an entry greater than 3. I assume I can use something similar to

m <- m[-grep("nchar(m$f_name)>3", m$f_name]

Answer 1

To reword your question slightly, you want to retain rows where entries in f_name have length of 3 or less. So how about:

subset(m, nchar(as.character(f_name)) <= 3)