How to cross-paste all combinations of two vectors (each-to-each)?
You can also do:
outer(c("a", "b"), c("c", "d"), FUN = "paste0")[1:4]
[1] "ac" "bc" "ad" "bd"
Both do.call
and outer
are valuable functions to play with. :)
Alternately, we can assign
x <- outer(c("a", "b"), c("c", "d"), FUN = "paste0")
dim(x) <- NULL
x
[1] "ac" "bc" "ad" "bd"
Without knowing the length.
More edits!
x <- outer(c("a", "b"), c("c", "d"), FUN = "paste0")
y <- t(x)
dim(y) <- NULL
y
[1] "ac" "ad" "bc" "bd"
Gets you the desired order, too.
Try this:
x <- c("a", "b")
y <- c("c", "d")
do.call(paste0, expand.grid(x, y))
# [1] "ac" "bc" "ad" "bd"
It is likely to be slower than outer
when x
and y
are long, but on the other hand it allows the following generalisation:
z <- c("e", "f")
do.call(paste0, expand.grid(x, y, z))
# [1] "ace" "bce" "ade" "bde" "acf" "bcf" "adf" "bdf"