Filtering a data frame by factors in R

Question

I have the following dataframe:

sp <- combn(c(\"sp1\",\"sp2\",\"sp3\",\"sp4\"),2)
d <- data.frame(t(sp),\"freq\"=sample(0:100,6))

and

Answer 1

Do not make x1 and x2 factors. Just use vectors. Use %in% for the logical test.

sp <- combn(c("sp1","sp2","sp3","sp4"),2)
d <- data.frame(t(sp),"freq"=sample(0:100,6))
x1 <- c("sp1","sp2")
x2 <- c("sp3","sp4")
sub <- d[d$X1 %in% x1 & d$X2 %in% x2,]