Forum: DirichletReg 0.4-0 on R-Forge
- 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.
- 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.
Marco J. Maier - 2014-12-12 11:25 -