Hi, I have a problem of estimating a mixture of two normal distributions. I need to find the starting points automatically, since this is a part of a larger piece of image processing code. I found the mix2normal1 function in VGAM package that mentions a method of finding starting values for mu1 and mu2 but refers the reader to a book by Everitt and Hand. Unfortunately, I do not have an easy access to this book. Could anybody point me to a description of the method that I could use? Any help will be appreciated. Thanks in advance, Andy __________________________________ Andy Jaworski 518-1-01 Process Laboratory 3M Corporate Research Laboratory ----- E-mail: apjaworski at mmm.com Tel: (651) 733-6092 Fax: (651) 736-3122
Hi, Try MCLUST package. You can use the hierarchical clustering to find the starting values of your EM. Xiaohui apjaworski at mmm.com wrote:> Hi, > > I have a problem of estimating a mixture of two normal distributions. I > need to find the starting points automatically, since this is a part of a > larger piece of image processing code. > > I found the mix2normal1 function in VGAM package that mentions a method of > finding starting values for mu1 and mu2 but refers the reader to a book by > Everitt and Hand. Unfortunately, I do not have an easy access to this > book. Could anybody point me to a description of the method that I could > use? > > Any help will be appreciated. Thanks in advance, > > Andy > > __________________________________ > Andy Jaworski > 518-1-01 > Process Laboratory > 3M Corporate Research Laboratory > ----- > E-mail: apjaworski at mmm.com > Tel: (651) 733-6092 > Fax: (651) 736-3122 > > ______________________________________________ > R-help at stat.math.ethz.ch 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. > >
Hi, you can also look at the function normalmix.init in the mixtools package. Tatiana Tatiana Benaglia Ph.D. Candidate Department of Statistics Penn State University On Feb 23, 2007, at 12:02 AM, apjaworski at mmm.com wrote:> Hi, > > I have a problem of estimating a mixture of two normal > distributions. I > need to find the starting points automatically, since this is a > part of a > larger piece of image processing code. > > I found the mix2normal1 function in VGAM package that mentions a > method of > finding starting values for mu1 and mu2 but refers the reader to a > book by > Everitt and Hand. Unfortunately, I do not have an easy access to this > book. Could anybody point me to a description of the method that I > could > use? > > Any help will be appreciated. Thanks in advance, > > Andy > > __________________________________ > Andy Jaworski > 518-1-01 > Process Laboratory > 3M Corporate Research Laboratory > ----- > E-mail: apjaworski at mmm.com > Tel: (651) 733-6092 > Fax: (651) 736-3122 > > ______________________________________________ > R-help at stat.math.ethz.ch 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.
If you don't have too much noise, the peaks in the derivative curves can be used: See: http://research.stowers-institute.org/efg/R/Statistics/MixturesOfDistributions/index.htm efg Earl F. Glynn Scientific Programmer Stowers Institute for Medical Research <apjaworski at mmm.com> wrote in message news:OF89608350.3A0617D7-ON8625728B.001ADEC6-8625728B.001BAD0C at mmm.com...> Hi, > > I have a problem of estimating a mixture of two normal distributions. I > need to find the starting points automatically, since this is a part of a > larger piece of image processing code.