This is my first time posting here, so please be kind ;-)
EDIT My question was closed before I had a chance to make the changes suggested to me. So I'm trying to do a better job now, thanks for everyone that answered so far!
QUESTION
How can I identify records/rows in data frame x.1
that are not contained in data frame x.2
based on all attributes available (i.e. all columns) in the most efficient way?
EXAMPLE DATA
> x.1 <- data.frame(a=c(1,2,3,4,5), b=c(1,2,3,4,5))
> x.1
a b
1 1 1
2 2 2
3 3 3
4 4 4
5 5 5
> x.2 <- data.frame(a=c(1,1,2,3,4), b=c(1,1,99,3,4))
> x.2
a b
1 1 1
2 1 1
3 2 99
4 3 3
5 4 4
DESIRED RESULT
a b
2 2 2
5 5 5
BEST SOLUTION SO FAR
by Prof. Brian Ripley and Gabor Grothendieck
> fun.12 <- function(x.1,x.2,...){
+ x.1p <- do.call("paste", x.1)
+ x.2p <- do.call("paste", x.2)
+ x.1[! x.1p %in% x.2p, ]
+ }
> fun.12(x.1,x.2)
a b
2 2 2
5 5 5
> sol.12 <- microbenchmark(fun.12(x.1,x.2))
> sol.12 <- median(sol.12$time)/1000000000
> sol.12
> [1] 0.000207784
A collection of all solutions tested so far is available at my blog
FINAL EDIT 2011-10-14
Here's the best solution wrapped into a function 'mergeX()':
setGeneric(
name="mergeX",
signature=c("src.1", "src.2"),
def=function(
src.1,
src.2,
...
){
standardGeneric("mergeX")
}
)
setMethod(
f="mergeX",
signature=signature(src.1="data.frame", src.2="data.frame"),
definition=function(
src.1,
src.2,
do.inverse=FALSE,
...
){
if(!do.inverse){
out <- merge(x=src.1, y=src.2, ...)
} else {
if("by.y" %in% names(list(...))){
src.2.0 <- src.2
src.2 <- src.1
src.1 <- src.2.0
}
src.1p <- do.call("paste", src.1)
src.2p <- do.call("paste", src.2)
out <- src.1[! src.1p %in% src.2p, ]
}
return(out)
}
)