[R] finite mixture model (2-component Weibull): plotting Weibull components?
Dear Knowledgeable R Community Members, Please excuse my ignorance, I apologize in advance if this is an easy question, but I am a bit stumped and could use a little guidance. I have a finite mixture modeling problem -- for example, a 2-component Weibull mixture -- where the components have a large overlap, and I am trying to adapt the "mclust" package which concern to normal mixture to solve this problem. I need to decompose that mixture into its 2 components which will need to be plotted. What I don't know how to do is: (1) restrict the number of components to 2 . (2) obtain and plot a component Weibull density (Note: my real dataset will not have peaks this well separated, but I needed to find a small example.) Any information you might be able to shed on this would be very much appreciated With appreciation for your help. Thank you in advance Cordially; Abdoul Aziz Junior NDOYE GREQAM Marseille. [[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.
Re: [R] finite mixture model (2-component Weibull): plotting Weibull components?
mclust doesn't do Weibull mixtures, only Gaussian ones (though you may approximate a Weibull by several Gaussians). You may look up the flexmix package, which either does it already or a method function can be provided to do it. There is also an example "fitting a mixture distribution" in Venables and Ripley's MASS book with normals (including plotting the density), which you could adapt for Weibull distributions by plugging in the corresponding functions for the Weibull. (1) restrict the number of components to 2 . Specify G=2 in mclust (if want to fit 2 Gaussians). (2) obtain and plot a component Weibull density Generally, adding a Weibull mixture density to a plot works by x <- seq(0,100,by=0.1) # or whatever reasonable choice of x-values lines(x,p*dweibull(x,s11,s12)+(1-p)*dweibull(x,s21,s22)) where p, s11, s12, s21, s22 are the mixture parameters. Regards, Christian *** --- *** Christian Hennig University College London, Department of Statistical Science Gower St., London WC1E 6BT, phone +44 207 679 1698 chr...@stats.ucl.ac.uk, www.homepages.ucl.ac.uk/~ucakche __ 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.
