Find Elements That Appear Multiple Times in R

Things under legendu.net/outdated are outdated technologies that the author does not plan to update any more. Please look for better alternatives.

** Things under legendu.net/outdated are outdated technologies that the author does not plan to update any more. Please look for better alternatives. **

freq = tapply(x, x, FUN=length, simplify=TRUE)
freq[freq > 1]
# or you can use
freq = table(x, useNA = "always")
freq[freq > 1]