On Mon, 2011-04-11 at 15:57 +0100, Prof Brian Ripley wrote: > I suspect you omitted some of the help page:
Yes. My apologies, I don't know how I missed that - I did read it several times aware that I might be overlooking something sensible such as the sentence you quote. Sorry for the noise. G > As they are written for speed, they blur over some of the subtleties > of ‘NaN’ and ‘NA’. > > So, given that (and that real NA is a specific NaN) I think it is > perfectly reasonable to claim they are consistent with mean. > > On Tue, 5 Apr 2011, Gavin Simpson wrote: > > > Dear List, > > > > I'm not even sure this is an issue or not, but ?rowMeans has: > > > > Value: > > > > A numeric or complex array of suitable size, or a vector if the > > result is one-dimensional. The ‘dimnames’ (or ‘names’ for a > > vector result) are taken from the original array. > > > > If there are no values in a range to be summed over (after > > removing missing values with ‘na.rm = TRUE’), that component of > > the output is set to ‘0’ (‘*Sums’) or ‘NA’ (‘*Means’), consistent > > with ‘sum’ and ‘mean’. > > > > However the output of mean() and rowMeans() is not exactly the same when > > all supplied values are missing. > > > >> mean(NA, na.rm = TRUE) > > [1] NaN > >> mean(rep(NA, 5), na.rm = TRUE) > > [1] NaN > >> rowMeans(matrix(rep(NA, 5), ncol = 5), na.rm = TRUE) > > [1] NA > > > > So in one sense, the outputs are not consistent: > > > >> is.nan(mean(rep(NA, 5), na.rm = TRUE)) > > [1] TRUE > >> is.nan(rowMeans(matrix(rep(NA, 5), ncol = 5), na.rm = TRUE)) > > [1] FALSE > > > > but in another they are: > > > >> is.na(mean(rep(NA, 5), na.rm = TRUE)) > > [1] TRUE > >> is.na(rowMeans(matrix(rep(NA, 5), ncol = 5), na.rm = TRUE)) > > [1] TRUE > > > > I'm not familiar enough with the details to know if this even matters, > > but wonder if something in the documentation needs a change or tweak to > > clarify what is returned. As I say, in one sense the outputs are not > > consistent. > > > >> sessionInfo() > > R version 2.13.0 beta (2011-04-04 r55298) > > Platform: x86_64-unknown-linux-gnu (64-bit) > > > > locale: > > [1] LC_CTYPE=en_GB.utf8 LC_NUMERIC=C > > [3] LC_TIME=en_GB.utf8 LC_COLLATE=en_GB.utf8 > > [5] LC_MONETARY=C LC_MESSAGES=en_GB.utf8 > > [7] LC_PAPER=en_GB.utf8 LC_NAME=C > > [9] LC_ADDRESS=C LC_TELEPHONE=C > > [11] LC_MEASUREMENT=en_GB.utf8 LC_IDENTIFICATION=C > > > > attached base packages: > > [1] stats graphics grDevices utils datasets methods > > [7] base > > > > loaded via a namespace (and not attached): > > [1] tools_2.13.0 > > > > Thanks, > > > > Gavin > > -- > > %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% > > Dr. Gavin Simpson [t] +44 (0)20 7679 0522 > > ECRC, UCL Geography, [f] +44 (0)20 7679 0565 > > Pearson Building, [e] gavin.simpsonATNOSPAMucl.ac.uk > > Gower Street, London [w] http://www.ucl.ac.uk/~ucfagls/ > > UK. WC1E 6BT. [w] http://www.freshwaters.org.uk > > %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% > > > > ______________________________________________ > > R-devel@r-project.org mailing list > > https://stat.ethz.ch/mailman/listinfo/r-devel > > > > -- > Brian D. Ripley, rip...@stats.ox.ac.uk > 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 -- %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% Dr. Gavin Simpson [t] +44 (0)20 7679 0522 ECRC, UCL Geography, [f] +44 (0)20 7679 0565 Pearson Building, [e] gavin.simpsonATNOSPAMucl.ac.uk Gower Street, London [w] http://www.ucl.ac.uk/~ucfagls/ UK. WC1E 6BT. [w] http://www.freshwaters.org.uk %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
