Subsetting a data frame to the rows not appearing in another data frame

Question

I have a data frame A with observations

    Var1   Var2  Var3
     1       3    4
     2       5    6
     4       5    7
     4       5    8
     6       7    9         


        

Answer 1

Another option:

C <- rbind(A, B)
C[!(duplicated(C) | duplicated(C, fromLast = TRUE)), ]

Output:

  Var1 Var2 Var3
3    4    5    7
4    4    5    8
5    6    7    9