RE: [R] model-based clustering

2004-04-13 Thread Liaw, Andy 
In the time that you posted the numerous uninformative messages, you can do
yourself a great favor by following the posting guide mentioned in the
footer.

Try:

install.packages(mclust)
library(mclust)
?mclust
example(mclust)

Andy

 From: Talita Leite
 
 Hello again,
 
 Let me explain this better. I've been working in clustering 
 methods during 
 this year and now i'm starting (or trying to) with 
 model-based clustering. 
 I've been searching for help to understand how the functions 
 works and i 
 found some. The problem is that i don't know the steps to follow. For 
 example: working with the data set IRIS. What steps do i have 
 to follow and 
 what functions do i have to use to make a good clustering? To 
 find the three 
 groups on that case?
 
 Thanks,
 
 Talita
 
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Re: [R] model-based clustering

2004-01-14 Thread maj 
The list could probably be more useful if you gave more details about your
data and the problem. I have written a bit of R code myself for fitting a
finite mixture of univariate Poissons by EM and found it very simple to
program in R. I suspect that your problem is multivariate, but that should
not present any difficulties.

The Snob program employs a fairly sophisticated model search strategy
based on the Minimum Message Length criterion. If you do not know much
about the solution that you are seeking it might be a good way to go. I
appreciate that Snob can be rather complex to set up and get going but I
think that you should be able to get quite a bit of help from the Monash
University people behind the program. They are usually quite keen to
encourage new users of Snob.

Murray Jorgensen


 Hello,

 I was wondering whether a Poisson mixture modeler/cluster analysis
 package is available for R. I scanned CRAN packages and couldn't find
 anything but I thought I'd ask. If not could anyone recommend a non-R
 open source package. I have found 'snob' but this program seems a bit
 hard to use in an automated, non interactive fashion.

 regards,
 Murad


 --
 Murad Nayal M.D. Ph.D.
 Department of Biochemistry and Molecular Biophysics
 College of Physicians and Surgeons of Columbia University
 630 West 168th Street. New York, NY 10032
 Tel: 212-305-6884 Fax: 212-305-6926

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Re: [R] model-based clustering

2004-01-14 Thread Murad Nayal 

Hello Murray,

thanks for the response. I would actually love to hear alternative
suggestions about the problem I am trying to solve. I just thought a
short question will be less of a burden on people's time and have a
higher chance of being answered.

basically the data sets I need to analyze contain 2000-1 objects.
each characterized by, depending on the data set, 9-20 attributes. all
integers greater than zero, typically the range is [0,1000] with numbers
 5 particularly common. there is no apriori reason why these objects
should cluster into discrete groups. and in fact when the data is
explored graphically (xgobi) it doesn't show an obvious clustering
pattern. however, with 9-20 dimensions involved, it is probably easy to
miss subtle patterns. I have tried clustering the data using a number of
standard approaches including hclust,kmeans,fanny etc. but these methods
didn't seem to be able to generate convincingly distinct, homogeneous
clusters. of course given the type of the data involved Poisson mixtures
seem like the natural choice.

I have experimented a bit with snob using contrived data sets (where you
know which class objects really belong to) and it has been fairly
promising, except maybe for snob's tendency to break the known classes
into multiple subclasses. 

I actually would like to try to code this in R. It would be very helpful
to me in fact if you can contribute any code/code fragments/examples
from your earlier work on this, either to the list or privately.

many thanks
Murad



[EMAIL PROTECTED] wrote:
 
 The list could probably be more useful if you gave more details about your
 data and the problem. I have written a bit of R code myself for fitting a
 finite mixture of univariate Poissons by EM and found it very simple to
 program in R. I suspect that your problem is multivariate, but that should
 not present any difficulties.
 
 The Snob program employs a fairly sophisticated model search strategy
 based on the Minimum Message Length criterion. If you do not know much
 about the solution that you are seeking it might be a good way to go. I
 appreciate that Snob can be rather complex to set up and get going but I
 think that you should be able to get quite a bit of help from the Monash
 University people behind the program. They are usually quite keen to
 encourage new users of Snob.
 
 Murray Jorgensen
 
 
  Hello,
 
  I was wondering whether a Poisson mixture modeler/cluster analysis
  package is available for R. I scanned CRAN packages and couldn't find
  anything but I thought I'd ask. If not could anyone recommend a non-R
  open source package. I have found 'snob' but this program seems a bit
  hard to use in an automated, non interactive fashion.
 
  regards,
  Murad
 
 
  --
  Murad Nayal M.D. Ph.D.
  Department of Biochemistry and Molecular Biophysics
  College of Physicians and Surgeons of Columbia University
  630 West 168th Street. New York, NY 10032
  Tel: 212-305-6884 Fax: 212-305-6926
 
  __
  [EMAIL PROTECTED] mailing list
  https://www.stat.math.ethz.ch/mailman/listinfo/r-help
  PLEASE do read the posting guide!
  http://www.R-project.org/posting-guide.html
 
 

-- 
Murad Nayal M.D. Ph.D.
Department of Biochemistry and Molecular Biophysics
College of Physicians and Surgeons of Columbia University
630 West 168th Street. New York, NY 10032
Tel: 212-305-6884   Fax: 212-305-6926

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