Exact matching has preference over partial matching: see ?pmatch. Your version of R is three versions obsolete: the latest version explains this in detail under ?`[.data.frame` and ?`[` (and maybe 2.5.0 does too).
Please do your homework before sending non-bugs to R-bugs. On Wed, 28 Nov 2007, [EMAIL PROTECTED] wrote: > Full_Name: Philip Kensche > Version: R version 2.5.0 (2007-04-23) > OS: Linux > Submission from: (NULL) (131.174.146.31) > > > I want to access a row of a data.frame() by using the row names as hash keys. Hmm, you mean you use character vector indices. No hashing is involved. > This works fine for most keys. > > Now consider the following data.frame(). > >> x <- data.frame(v=c(V40="a", V411="b")) > >> x > v > V40 a > V411 b > > If I query for "V41", which does not exist in the data.frame() the call > does not return NA as I would expect but the row "V411". > >> x[ "V41", ] > [1] b > Levels: a b > > If there the prefix is not unique the query does not return a results, i.e. > >> x <- data.frame(v=c(V412="a", V411="b")) > >> x > v > V412 a > V411 b > >> x[ "V41", ] > [1] <NA> > Levels: a b > > > sessionInfo() output: >> sessionInfo() > R version 2.5.0 (2007-04-23) > i686-pc-linux-gnu > > locale: > LC_CTYPE=en_US;LC_NUMERIC=C;LC_TIME=en_US;LC_COLLATE=en_US;LC_MONETARY=en_US;LC_MESSAGES=en_US;LC_PAPER=en_US;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC_MEASUREMENT=en_US;LC_IDENTIFICATION=C > > attached base packages: > [1] "stats" "graphics" "grDevices" "utils" "datasets" "methods" > [7] "base" > > other attached packages: > lattice > "0.15-4" > > ______________________________________________ > 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
