Then the answer is pretty simple: 'no'. The idea probably needs a lot more refining to make it workable, too. Why do you discard he peak at 2, with the shape starting at 1 and finishing at 4, for example?
In thinking about this it might be useful for you to look at signs of successive differences: > sign(diff(c(-Inf, x))) [1] 1 1 -1 -1 1 1 1 1 1 -1 -1 -1 -1 -1 1 -1 That's perhaps a starting point. You seem to want to know (roughly) "where do the runs of '1's start and the following run of '-1's end?" The function rle(), for run length encoding, might be useful in this regard, too. Bill Venables. -----Original Message----- From: Research Scholar [mailto:[EMAIL PROTECTED] Sent: Tuesday, 25 March 2008 1:24 PM To: Venables, Bill (CMIS, Cleveland) Cc: r-help@r-project.org Subject: Re: [R] peak finding Hi Thanks for replying. I meant x[4] is the start of a peak shape and x[14] is the end of that peak and x[9] is the maxima of the peak. Thanks, John On Mon, Mar 24, 2008 at 11:09 PM, <[EMAIL PROTECTED]> wrote: It's hard to see how positions 4 and 14 correspond to 'peaks', they look like troughs to me. So perhaps this is what you mean: > x <- c(14,15,12,11,12,13,14,15,16,15,14,13,12,11,14,12) > y <- which(x == min(x)) > y [1] 4 14 as a function: somefunction <- function(x) which(x == min(x)) Bill Venables CSIRO Laboratories PO Box 120, Cleveland, 4163 AUSTRALIA Office Phone (email preferred): +61 7 3826 7251 Fax (if absolutely necessary): +61 7 3826 7304 Mobile: +61 4 8819 4402 Home Phone: +61 7 3286 7700 mailto:[EMAIL PROTECTED] http://www.cmis.csiro.au/bill.venables/ -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Research Scholar Sent: Tuesday, 25 March 2008 12:54 PM To: r-help@r-project.org Subject: [R] peak finding Hi all Is there a function that can find the start and end position of peaks in a set of numbers. eg. x <- c(14,15,12,11,12,13,14,15,16,15,14,13,12,11,14,12) y <- somefunction(x) y 4 14 Thanks John [[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. ______________________________________________ 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.
