On Thu, 28 Sep 2006, Christoph Buser wrote: > Dear Brian > > Thank you for your answer and the comment you included on the > apply() help page. > > 1) > > You are correct. My data.frame is coerced into a matrix in > apply() > > 2) > > I agree that the new version of unlist() is better and works > correctly and that in array() (due to as.vector()) the factor > "ans" is coerced into a character matrix. > > Nevertheless I disagree that this is "feature freeze" with > R version 2.3.1:
It is R 2.4.0 that is in 'feature freeze': we cannot change 2.4.0 now (and would not have done so when I answered). See developer.r-project.org for a fuller explanation. > Since in R-2.3.1, unlist() on a list of factors returned an > integer vector, the result of apply was an integer matrix and > not a character matrix. > > Therefore my question is if it would be desirable to return an > integer matrix by changing apply. One could include additional > code to handle the case if the output "should" be a factor > matrix and coerce into an integer matrix. > > Then the outcome would be consistent with R-2.3.1 without > changing something in unlist() or array(). > > > But in the end I am not sure if an integer matrix is better than > a character matrix or a factor matrix. I am not sure what output > is best if one uses as.factor in apply. It seems best not to do so! > > Regards, > > Christoph > > -------------------------------------------------------------- > Christoph Buser <[EMAIL PROTECTED]> > Seminar fuer Statistik, LEO C13 > ETH Zurich 8092 Zurich SWITZERLAND > phone: x-41-44-632-4673 fax: 632-1228 > http://stat.ethz.ch/~buser/ > -------------------------------------------------------------- > > Prof Brian Ripley writes: > > Christoph, > > > > This is more complicated than your analysis. > > > > 1) apply takes a matrix as an argument, not a data frame, and so first > > coerced 'dat' to a character matrix. > > > > 2) unlist is working quite correctly. The issue is array(), which > > contains as.vector(data). Thus although the result could be a factor > > matrix, as.vector is coercing it to a character matrix. It might be > > desirable to return a factor matrix, but we are not going to do that in > > feature freeze (if ever) and I really don't think it would be what you > > wanted. > > > > Perhaps the help page should contain an explicit statement that the result > > will be coerced to a basic vector type by as.vector(). > > > > On Mon, 25 Sep 2006, Christoph Buser wrote: > > > > > Dear R-core > > > > > > There is a different output for the apply function due to the > > > change of unlist as mentioned in the R news. > > > > > > Newly, applying as.factor() (or factor()) in > > > > > > str(dat <- data.frame(x = 1:10, f1 = gl(2,5,labels = c("A", "B")))) > > > (d1 <- apply(dat,2,as.factor)) > > > > > > newly returns a character matrix while in R-2.3.1 the same > > > command resulted in an integer matrix that was consistent (up to > > > the ordering of the factor levels) with data.matrix(). > > > > That's coincidence -- try x=11:20. > > > > > The change is caused by the change of unlist() that, used for a > > > list of factors, newly returns a single factor instead of an > > > integer. I am happy with this change, but: > > > > > > Is it desirable to change apply so that it does not return a > > > character matrix in the example above or include a warning for > > > such a case? > > > > > > Thank you very much for an answer. > > > > > > Regards, > > > > > > Christoph Buser > > > > > > -------------------------------------------------------------- > > > Christoph Buser <[EMAIL PROTECTED]> > > > Seminar fuer Statistik, LEO C13 > > > ETH Zurich 8092 Zurich SWITZERLAND > > > phone: x-41-44-632-4673 fax: 632-1228 > > > http://stat.ethz.ch/~buser/ > > > > > > ______________________________________________ > > > R-devel@r-project.org mailing list > > > https://stat.ethz.ch/mailman/listinfo/r-devel > > > > > > > -- > > Brian D. Ripley, [EMAIL PROTECTED] > > Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ > > University of Oxford, Tel: +44 1865 272861 (self) > > 1 South Parks Road, +44 1865 272866 (PA) > > Oxford OX1 3TG, UK Fax: +44 1865 272595 > > ______________________________________________ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel > -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
