Checking if string is in uppercase in R

If you prefer to live in a tidyr universe, here's the version using stringr:

library(stringr)
str_detect(s, "^[:upper:]+$")

Why not just test if the word is identical to itself when converted to upper case with the "toupper" function?

word1 <- "TEST"
word1 == toupper(word1) 

will be TRUE

You can use the ^ and $ patterns to match the beginning and end of the string

grepl("^[[:upper:]]+$", s)