R filtering out a subset

Question

I have a data.frame A and a data.frame B which contains a subset of A

How can I create a data.frame C which is data.frame A with data.frame B excluded? Thanks for your h

Answer 1

A <- data.frame(x = 1:10, y = 1:10)
#Random subset of A in B
B <- A[sample(nrow(A),3),]
#get A that is not in B
C <- A[-as.integer(rownames(B)),]

Performance test vis-a-vis mplourde's answer:

library(rbenchmark)
f1 <- function() A[- as.integer(rownames(B)),]
f2 <- function() A[! data.frame(t(A)) %in% data.frame(t(B)), ]
benchmark(f1(), f2(), replications = 10000, 
          columns = c("test", "elapsed", "relative"),
          order = "elapsed"
          )

  test elapsed relative
1 f1()   1.531   1.0000
2 f2()   8.846   5.7779

Looking at the rownames is approximately 6x faster. Two calls to transpose can get expensive computationally.