Dear all, from the help page of quantile:
"x numeric vectors whose sample quantiles are wanted. Missing values are ignored." from the help page of IQR: "x a numeric vector." as a matter of facts it seems that both quantile() and IQR() do not check for the presence of a numeric input. See the following: set.seed(11) x <- rbinom(n=11,size=2,prob=.5) x <- factor(x,ordered=TRUE) x [1] 1 0 1 0 0 2 0 1 2 0 0 Levels: 0 < 1 < 2 > quantile(x) 0% 25% 50% 75% 100% 0 <NA> 0 <NA> 2 Levels: 0 < 1 < 2 Warning messages: 1: In Ops.ordered((1 - h), qs[i]) : '*' is not meaningful for ordered factors 2: In Ops.ordered(h, x[hi[i]]) : '*' is not meaningful for ordered factors > IQR(x) [1] 1 whereas median has the check: > median(x) Error in median.default(x) : need numeric data I also take the opportunity to ask your comments on the following related subject: In my opinion it would be convenient that median() and the like (quantile(), IQR()) be implemented for ordered factors for which in fact they can be well defined. For instance, in this way functions like apply(x,FUN=median,...) could be used without the need of further processing for data frames that contain both numeric variables and ordered factors. If on the one hand, to my limited knowledge, in English introductory statistics textbooks the fact that the median is well defined for ordered categorical variables is only mentioned marginally, on the other hand, in the Italian Statistics literature this is often discussed in detail and this could mislead students and practitioners that might expect median() to work for ordered factors. In this message https://stat.ethz.ch/pipermail/r-help/2003-November/042684.html Martin Maechler considers the possibility of doing such a job by allowing for extra arguments "low" and "high" as it is done for mad(). I am willing to give a contribution if requested, and comments are welcome. Thank you for the attention, kind regards, Simone > R.version _ platform i386-pc-mingw32 arch i386 os mingw32 system i386, mingw32 status major 2 minor 8.1 year 2008 month 12 day 22 svn rev 47281 language R version.string R version 2.8.1 (2008-12-22) LC_COLLATE=Italian_Italy.1252;LC_CTYPE=Italian_Italy.1252;LC_MONETARY=Italian_Italy.1252;LC_NUMERIC=C;LC_TIME=Italian_Italy.1252 -- ______________________________________________________ Simone Giannerini Dipartimento di Scienze Statistiche "Paolo Fortunati" Universita' di Bologna Via delle belle arti 41 - 40126 Bologna, ITALY Tel: +39 051 2098262 Fax: +39 051 232153 http://www2.stat.unibo.it/giannerini/ ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
