Yes, but either drop(t(df[,1,drop=TRUE]))
or t(df[,1,drop=TRUE])[1,] does work. My minimal effort to check timings found that the first version was a hair faster. -- Bert On Sat, Aug 18, 2012 at 9:01 AM, Rui Barradas <ruipbarra...@sapo.pt> wrote: > Hello, > > A bit more general > > nv <- c(a=1, d=17, e=101); nv > nv2 <- c(a="a", d="d", e="e") > df2 <- data.frame(VAR = nv, CHAR = nv2); df2 > > identical( nv, drop(t( df2[1] )) ) # TRUE > identical( nv, drop(t( df2[[1]] )) ) # FALSE > > Rui Barradas > > Em 18-08-2012 16:16, Joshua Ulrich escreveu: >> >> I don't know if this is better, but it's the most obvious/shortest I >> could come up with. Transpose the data.frame column to a 'row' vector >> and drop the dimensions. >> >> R> identical(nv, drop(t(df))) >> [1] TRUE >> >> Best, >> -- >> Joshua Ulrich | about.me/joshuaulrich >> FOSS Trading | www.fosstrading.com >> >> >> On Sat, Aug 18, 2012 at 10:03 AM, Martin Maechler >> <maech...@stat.math.ethz.ch> wrote: >>> >>> Today, I was looking for an elegant (and efficient) way >>> to get a named (atomic) vector by selecting one column of a data frame. >>> Of course, the vector names must be the rownames of the data frame. >>> >>> Ok, here is the quiz, I know one quite "cute"/"slick" answer, but was >>> wondering if there are obvious better ones, and >>> also if this should not become more idiomatic (hence "R-devel"): >>> >>> Consider this toy example, where the dataframe already has only >>> one column : >>> >>>> nv <- c(a=1, d=17, e=101); nv >>> >>> a d e >>> 1 17 101 >>> >>>> df <- as.data.frame(cbind(VAR = nv)); df >>> >>> VAR >>> a 1 >>> d 17 >>> e 101 >>> >>> Now how, can I get 'nv' back from 'df' ? I.e., how to get >>> >>>> identical(nv, .......) >>> >>> [1] TRUE >>> >>> where ...... only uses 'df' (and no non-standard R packages)? >>> >>> As said, I know a simple solution (*), but I'm sure it is not >>> obvious to most R users and probably not even to the majority of >>> R-devel readers... OTOH, people like Bill Dunlap will not take >>> long to provide it or a better one. >>> >>> (*) In my solution, the above '.......' consists of 17 letters. >>> I'll post it later today (CEST time) ... or confirm >>> that someone else has done so. >>> >>> Martin >>> >>> ______________________________________________ >>> R-devel@r-project.org mailing list >>> https://stat.ethz.ch/mailman/listinfo/r-devel >> >> ______________________________________________ >> R-devel@r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-devel > > > ______________________________________________ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel -- Bert Gunter Genentech Nonclinical Biostatistics Internal Contact Info: Phone: 467-7374 Website: http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
