hello again!
there is an error in my previous post:
your.string <- "aaacdf"
nc1 <- nchar(your.string)-1
x <- unlist(strsplit(your.string, NULL)) ######## CORRECT
x2 <- c()
for (i in 1:nc1)
x2 <- c(x2, paste(x2[i], x2[i+1], sep=""))
cat("ocurrences of <aa> in <your.string>:", length(grep("aa", x2)),
sep="", fill=TRUE)
Hope it helps!
Fran