Remove all rows where length of string is more than n

问题

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]

回答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)

回答2:

Try this:

m[!nchar(as.character(m$f_name)) > 3, ]

回答3:

For those looking for a tidyverse approach, you can use dplyr::filter:

m %>% dplyr::filter(nchar(f_name) > 3)

来源：https://stackoverflow.com/questions/8640377/remove-all-rows-where-length-of-string-is-more-than-n