Yes Gabor, you definition (a sequence of numbers which each increase by 1 over the prior number) is what I meant. Sorry it that was not clear and I thank you and Joshua for your time and your explanation. This should work fine.
Gabor Grothendieck wrote: > > On Wed, Jul 6, 2011 at 7:32 PM, B77S <bps0...@auburn.edu> wrote: >> Hi, >> >> How can I discern which elements in x (see below) are in 'order', but >> more >> specifically.. only the 1st 'ordered run'? >> I would like for it to return elements 1:8... there may be ordered values >> after 1:8, but those are not of interest. >> >> x <- c(1, 2, 3, 4, 5, 6, 7, 8, 20, 21, 22, 45) >> >> > > Since the definition of an ordered run is not given we assume that it > is a sequence of numbers which each increase by 1 over the prior > number. If that is not it then you will need to clarify the problem > definition. > > First calculate a logical vector which is TRUE at each position which > starts a new run. Note that the first position in x always starts a > new run even if that run is a singleton so it can be set to TRUE. The > remaining elements can be computed using diff as shown. The > resulting logical vector is the argument to cumsum below. > > Taking the cumulative sum of this logical vector gives a vector the > same length as x but with each element of the 1st run replaced with 1, > each element of the 2nd run replaced with 2 and so on. > > Finally, since we only want the 1st run we pick out those positions of > x where the cumsum equals 1. > >> x[cumsum(c(TRUE, diff(x) != 1)) == 1] > [1] 1 2 3 4 5 6 7 8 > > > -- > Statistics & Software Consulting > GKX Group, GKX Associates Inc. > tel: 1-877-GKX-GROUP > email: ggrothendieck at gmail.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. > -- View this message in context: http://r.789695.n4.nabble.com/identifying-a-run-in-a-vector-tp3650295p3650509.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.
