Hi Jim I was following this thread and found that your answer is perfect there. However I could not comprehend the meaning of the expression " cumsum(x == 0)". If I paste it in R window, I get following :
> cumsum(x == 0) [1] 1 2 2 2 2 3 4 4 4 4 I gone through the help page of cumsum() function I correctly understand that this function calculates the cumulative sum. But could not understand really the meaning of cumsum(x == 0) Would you please explain that? Thanks, -----Original Message----- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of jim holtman Sent: 08 March 2010 08:32 To: Daren Tan Cc: r-h...@stat.math.ethz.ch Subject: Re: [R] Average regions of non-zeros Try this: > x <- c(0,0,1,2,3,0,0,4,5,6) > # partition the data > x.p <- split(x, cumsum(x == 0)) > # now only process groups > 1 > x.mean <- lapply(x.p, function(a){ + if (length(a) == 1) return(NULL) + return(list(grp=tail(a, -1), mean=mean(tail(a, -1)))) + }) > # now only return the real values > x.mean[unlist(lapply(x.mean, length) != 0)] $`2` $`2`$grp [1] 1 2 3 $`2`$mean [1] 2 $`4` $`4`$grp [1] 4 5 6 $`4`$mean [1] 5 On Sun, Mar 7, 2010 at 9:48 PM, Daren Tan <dare...@hotmail.com> wrote: > > x <- c(0,0,1,2,3,0,0,4,5,6) > > > > How to identify the regions of non-zeros and average c(1,2,3) and c(4,5,6) > to get 2 and 5. > > > > Thanks > > > > _________________________________________________________________ > Hotmail: Trusted email with Microsofts powerful SPAM protection. > > [[alternative HTML version deleted]] > > > ______________________________________________ > 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<http://www.r-project.org/posting -guide.html> > and provide commented, minimal, self-contained, reproducible code. > > -- Jim Holtman Cincinnati, OH +1 513 646 9390 What is the problem that you are trying to solve? [[alternative HTML version deleted]] ______________________________________________ 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.
