Identifying duplicates in a list of character vectors in R

Question

I have a list of character vectors like this:

my_list <- list(c('a','b','c','d','e'),c('e','f','g'),c('h','i','j'))
names(my_list) <- c("group1","group2","group3")

And I want to have a simple way to test my_list for duplicates in the letters across any of the 3 groups/vectors in my list. So for instance, "e" appears in both group 1 and group 2 so that would be a duplicate. Anything simple that just returns a logical if there is at least one or more duplicates across 2 or more groups would be ideal. So a FALSE return would mean that the letters in each group are unique to that group only (this isn't the case in my example here obviously).

Thanks so much!

Answer 1

A binary output can be generated with

any(duplicated(unlist(my_list)))
[1] TRUE

As pointed out correctly in comments by @sindri_baldur, if duplicates appear in groups they should be handled with unique, if desired:

any(duplicated(unlist(lapply(my_list, unique))))
[1] TRUE

or another base R alternative

anyDuplicated(unlist(lapply(my_list, unique))) > 1
[1] TRUE