[DirichletReg-News] DirichletReg 0.4-0 on R-Forge

[Marco Maier]

dear DirichletReg users,


as of now, the new version of my package (0.4-0) is available for all
platforms and architectures via r-forge. you can install it as always
by
  > install.packages("DirichletReg", repos="http://R-Forge.R-project.org")


NB: r-forge only builds for the latest version of R, so you will have
to upgrade to R 2.15.0 to use this version; but there are good
reasons to do so - see below.


there have been quite a lot of changes, fixes, and improvements, but
mostly internal, hence invisible for users. some new features are:

- the data structure of objects generated by DR_data() has been
  changed. it is no longer a list, but now a numeric matrix of class
  "DirichletRegData" with lots of attributes. this permits you to
  store the processed data in the original data.frame to keep your
  workspace tidy, e.g.,
    > ArcticLake$Y <- DR_data(ArcticLake[, 1:3])
  so you can fit a model like:
    > DirichReg(Y ~ depth, ArcticLake)
  note that `free floating' dependent variables (i.e., not part of
  the data.frame) can also be used, as in prior versions.
  
- formula processing is now handled by the package `Formula' which is
  much more robust than my `homemade' routines in earlier versions
  and has the advantage that

- there is an update() method for Dirichlet regression models. so if
  you fit a model like
    > res1 <- DirichReg(Y ~ depth + I(depth^2), ArcticLake)
  you can easily omit, e.g., the quadratic term for `sand' by typing
    > res2 <- update(res1, . ~ . -I(depth^2))
  instead of having to specify a completely new model like
    > DirichReg(Y ~ depth | depth + I(depth^2) | depth + I(depth^2),
        ArcticLake)
  therefore, model selection is made a lot easier.

- i did my best to complete the documentation which was a little
  fragmentary for some topics.
  
- optimization settings have been tweaked and estimation is now both,
  faster, and more robust.
  
- the package is now, by default, byte-compiled and therefore even
  faster (byte-compilation is now a standard feature for R >= 2.15.0
  and another good reason to upgrade).

- some new methods for the class "DirichletRegModel" have been
  implemented.

- DirichReg() has a couple of useful new features (subset, weights,
  etc.).

- lots more ... please consult the documentation and have a look at
  the examples.


as always: if you have any questions, suggestions, ..., please
contact me directly or via r-forge (e.g., using the `trackers' for
requests or bugs)


thanks for using my package + kind regards,
marco





Mag. Marco J. Maier
Institut für Statistik und Mathematik
Institute for Statistics and Mathematics

WU
Wirtschaftsuniversität Wien
Vienna University of Economics and Business
Augasse 2-6
1090 Wien
Austria

Tel: +43-1-313 36-4335
Fax: +43-1-313 36-774
E-Mail: marco.maier at wu.ac.at
www.wu.ac.at

http://statmath.wu.ac.at/~maier