Jaccard Coefficient in R

Question

I have some trouble understanding what seems to be pretty easy calculation.

I understand Jaccard coefficient is intersection(A,B)/union(A,B), so how come this is true?

> sets::gset_similarity(c("1","2"), c("1","2","3"), "Jaccard")
[1] 1

Isn't it 2/3?

Answer 1

It works if you pass it actual set data (see ?sets::set):

gset_similarity(set("1","2"), set("1","2","3"), "Jaccard") 
#[1] 0.6666667

Or

gset_similarity(as.set(c("1","2")), as.set(c("1","2","3")), "Jaccard")
#[1] 0.6666667

...if you have existing vectors and need to convert them.