r - How to create a function that prints the number of identical values in three vectors?

Question

please...can you tell me how can I create a function that finds the number of identical values in three vectors? And the result should be 2. (beause 8. and 10. are same in vectors) The vectors are:

a = 1:10
b = 4:15
d = c(8, 10, 18)

question from:https://stackoverflow.com/questions/65887857/how-to-create-a-function-that-prints-the-number-of-identical-values-in-three-vec

Answer 1

I think the most efficient way is the answer by @Dason. Below is another option with mapply + rowSums

v <- list(a,b,d)
sum(rowSums(mapply(`%in%`,list(unique(unlist(v))),v))==length(v))

which gives

[1] 2