Hi, Thanks a lot for your reply - I posted a second message where I provide a "dummy" example, entitled "How to improve the robustness of "loess"? - example included".
I need to fit a curve which makes it a bit difficult to work with kde2d only. I'm actually trying to use kde2d in combination with loess - basically I give the output density of kde2d as weights in the "loess" function. It seems to give nice results :) In my second post I wrote that the "weight" option did not work but that's because I was writing "weigth" - not sure why I did not get an error message. I'll post the lines of code as a reply to the second post. All the best, Emmanuel On 10 March 2012 19:46, David Winsemius <dwinsem...@comcast.net> wrote: > > On Mar 10, 2012, at 3:55 PM, Emmanuel Levy wrote: > >> Hi, >> >> I'm trying to normalize data by fitting a line through the highest density >> of points (in a 2D plot). >> In other words, if you visualize the data as a density plot, the fit I'm >> trying to achieve is the line that goes through the "crest" of the >> mountain. > > > Are you familiar with the kde2d of bkde2D functions in various packages? If > you then collected the max density for each X and Y you might want to see > whether that 2-d function would follow a sufficiently regular path that > would represent the projection of the ridge on the z=0 plane. > > >> >> This is similar yet different to what LOESS does. > > > Do you want a curve or a line? > > >> I've been using loess >> before, but it does not exactly that as it takes into account all points. >> Although points farther from the fit have a smaller weight, they result in >> the fit being a bit off the crest. >> >> Do you know a package or maybe even an option in loess that would allow me >> achieve this? > > > I don't. I happen to have a dataset where I could test it. But you are > likely to get better responses if you provide a test case. > >> Any advice or idea appreciated. >> >> Emmanuel >> >> [[alternative HTML version deleted]] > > > Plain text is preferred. > > -- > > David Winsemius, MD > West Hartford, CT > ______________________________________________ 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.