Hi Ding, While I was completely off the track in my first reply, the subsequent posts make your problem somewhat clearer. The way you state the problem suggests that the order of the values of "freq" is important. That is, it is not just a matter of finding local maxima, but the direction in which you approach those maxima is important. For example. I might want to only identify maxima with at least four monotonically increasing values preceding them and a decrease of at least half the value of the maximum in the succeeding value. By breaking down the problem into a set of criteria, these can be implemented in a function that will search the values in one direction, returning the locations of maxima that fulfil those criteria.
Jim On Mon, Mar 16, 2020 at 3:11 PM Yuan Chun Ding <ycd...@coh.org> wrote: > > sorry, I just came back. > > Yes, Abby's understanding is right. > > > tem4$Var1 > [1] 1 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 20 > 21 22 23 24 25 31 > > tem4$Freq > [1] 1 2 5 5 10 4 4 8 1 1 8 8 2 4 3 1 > 2 1 1 138 149 14 1 1 > > I have 2000 markers, this is just one example marker, the var1 is a VNTR > marker with alleles 1, 3, 4 etc, a multi-allele marker; the corresponding > frequency for each allele is 1,2 5 etc. I want to convert this multi-allele > marker to bi-allele markers by choosing a cutoff value; I would want the cut > point to be allele 6 with frequency of 10, so allele 1 to allele 9 are > considered as "short" allele, allele 10 to 31 as "long" allele; then sliding > to next rsing frequency peak, allele 8 with frequency of 8, etc. > > maybe those rising peaks are not really multiple modes, but I want to do this > type of data conversion. I want to first determine the number of modes, then > convert input dat file into m different input files, then perform Cox > regression analysis for each converted file. I am stuck in the step of find > out m rise peaks. > > Thank you, > > Ding > ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
