v1 <- c(1,2)
    v2 <- c(1,3)
    v3 <- c(2,1)
    df.test <- data.frame(rbind(v1,v2,v3))
    colnames(df.test) <- c('from', 'to')

c <- c()

    for (row in 1:nrow(df.test)) {
        from <- df.test[row, "from"]
        to  <- df.test[row, "to"]
        new.row <- c(from, to)
        c <- c(c, new.row)

        # having trouble storing unique values here...


     }