The following code example contains an easy error in using the Rfunction
unique().vec1 <- c("a", "b", "c") vec2 <- c("c", "d") unique(vec1, vec2) #  "a" "b" "c"
Notice none of the novel values from
vec2are present in the result. Our mistake was: we (improperly) tried to use
unique()with multiple value arguments, as one would use
union(). Also notice no error or warning was signaled. We used
unique()incorrectly and nothing pointed this out to us. What compounded our error was
...” function signature feature.
John makes it clear that
... is not itself a bad thing, just that there is a time and a place for it and misusing it can lead to hard-to-understand bugs.