Phil's algorithm is a good one, unless you're worried about optimizing for speed. It makes N * M comparisons, where N is the length of the first vector and M is the length of the second. Explicitly iterating through the longer vector, you could reduce the number of comparisons to M. As is often the case, here there's a tradeoff between human effort and computer effort.
OTOH, because explicit iteration incurs higher interpretation costs in R, it could conceivably be that Phil's algorithm performs faster. I don't know. -- View this message in context: http://n4.nabble.com/Count-matches-of-a-sequence-in-a-vector-tp2019018p2019428.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
