Chopping a string into a vector of fixed width character elements

Question

I have an object containing a text string:

x <- "xxyyxyxy"

and I want to split that into a vector with each element containing two letters:

[1] "xx" "yy" "xy" "xy"

It seems like the strsplit should be my ticket, but since I have no regular expression foo, I can't figure out how to make this function chop the string up into chunks the way I want it. How should I do this?

Answer 1

Using substring is the best approach:

substring(x, seq(1, nchar(x), 2), seq(2, nchar(x), 2))

But here's a solution with plyr:

library("plyr")
laply(seq(1, nchar(x), 2), function(i) substr(x, i, i+1))