mydata <- data.frame(
    ID = c(1:4),
    tag1 = c(1, 0, 1, 0),
    tag2 = c(0, 0, 0, 0),
    tag3 = c(1, 0, 1, 1),
    tag4 = c(1, 1, 0, 1),
    tag5 = c(0, 1, 1, 1)
)

mydata2 <- data.frame(
    ID = c(1,1,1,2,3,3,3,4,4,4),
    target = c("tag1","tag1","tag3","tag4","tag1","tag1","tag3","tag3","tag3","tag4"),
    source = c("tag3","tag4","tag4","tag5","tag3","tag5","tag5","tag4","tag5","tag5")
)