<fb7c7e870910080701o1683a41q7d4295d97af8c...@mail.gmail.com> Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0
Hi=2C =20 Thanks so much for your answer. It works beautifully for my example and of = course i will test it on the"real" data as well. =20 Thanks again=2C =20 Monica ________________________________ > Date: Thu=2C 8 Oct 2009 16:01:36 +0200 > Subject: Re: [R] intersection of 2 density curves > From: r.m.k...@gmail.com > To: pisican...@hotmail.com > CC: r-h...@stat.math.ethz.ch > > > > On Thu=2C Oct 8=2C 2009 at 3:48 PM=2C Monica Pisica> wrote: > > > > > > Hi=2C > > > > I would like to find out the coordinates of the intersection points of 2 = density curves. I did a search but i didn't get any significant results. I = really hope some of you have some ideas. here it is an example: > > > > set.seed(123) > > x1 <- rnorm(100=2C 1=2C 1) > > x2 <- rnorm(100=2C 0=2C 1) > > d1 <- density(x1) > > d2 <- density(x2) > > > > plot(d1=2C col =3D 2) > > lines(d2=2C col =3D 4) > > > > if you specify n=2C from ant to in density() and keep them the same=2C th= en the density estimates are done for the same x-coordinates. Therefore you= can compare d1$y with d2$y to deternine=2C where they intersect: > > > d2 <- density(x2=2C from=3D-3=2C to=3D5=2C n=3D2048) > d1 <- density(x1=2C from=3D-3=2C to=3D5=2C n=3D2048) > plot(d1=2C col =3D 2) > lines(d2=2C col =3D 4) > d1$y < d2$y > intersX <- d1$x[as.logical(abs(diff(d1$y < d2$y)))] > > intersY <- d1$y[as.logical(abs(diff(d1$y < d2$y)))] > > abline(v=3Dinters) > abline(h=3DintersY) > > Cheers=2C > > Rainer > > > Now i would like to know the coordinates of the intersection point. I did= some "trial and error" and i come up with these .... (that means i did sev= eral vertical and horizontal lines through the graph until visually i "hit"= the intersection point) > > > > > abline(v =3D 0.35=2C lty =3D 2) > > abline(h =3D 0.34=2C lty =3D 2) > > > > I really appreciate any hints you may have=2C thanks so much=2C > > > > Monica > > _________________________________________________________________ > > > http://clk.atdmt.com/GBL/go/171222985/direct/01/ > > ______________________________________________ > > 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.h= tml > > and provide commented=2C minimal=2C self-contained=2C reproducible code. > > > > > -- > Rainer M. Krug=2C PhD (Conservation Ecology=2C SUN)=2C MSc (Conservation = Biology=2C UCT)=2C Dipl. Phys. (Germany) > > Centre of Excellence for Invasion Biology > Natural Sciences Building > > Office Suite 2039 > Stellenbosch University > Main Campus=2C Merriman Avenue > Stellenbosch > South Africa > > Cell: +27 - (0)83 9479 042 > Fax: +27 - (0)86 516 2782 > Fax: +49 - (0)721 151 334 888 > > email: rai...@krugs.de > > Skype: RMkrug > Google: r.m.k...@gmail.com > =0A= _________________________________________________________________=0A= ______________________________________________ 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.
