Le 20 Avril 2005 16:05, A.J. Rossini a écrit : > x[-length(x)] ? I feel idiot from that one, but hold on to my point. ;-)
Better example, then: how about a compact way to drop, say, the last 3 elements of a vector? I think > tail(x, -3) would be nicer --- and more readable --- than > x[-((length(x)-2):length(x))] or > x[0:3 -length(x)] or some other convoluted way to achieve the same result. (BTW, dropping the last element of a vector would be 'tail(x, -1)., not 'tail(x, -length(x))' as stated in my original post. The latter would drop all the elements.) > On 4/20/05, Vincent Goulet <[EMAIL PROTECTED]> wrote: > > Dear R developers, > > > > I'm a former APL programmer. In that language, the "take" (up arrow) and > > "drop" (down arrow) operators were extensively used to, well, take and > > drop elements of vectors. Functions head() and tail() are equivalents in > > R for the "take" operator, but nothing seems to mimic the "drop" > > operator. I think it would be useful. > > > > For example, is there any simpler way to extract all elements of a vector > > but the last one than doing > > > > > x[1:(length(x) - 1)] ? > > > > An equivalent of "drop" would make this easy. > > > > Now, I think this could be easily implemented with the existing functions > > by allowing negative arguments to head() and tail(). For example, > > > > > head(x, -1) > > > > would drop the first element of a vector and > > > > > tail(x, -length(x)) > > > > the last one. > > > > Is there any interest for such an extension? > > > > I would be very willing to contribute a patch, although I don't have much > > experience in doing so. > > > > Best regards, > > > > -- > > Vincent Goulet, Associate Professor > > École d'actuariat > > Université Laval, Québec > > [EMAIL PROTECTED] http://vgoulet.act.ulaval.ca > > > > ______________________________________________ > > R-devel@stat.math.ethz.ch mailing list > > https://stat.ethz.ch/mailman/listinfo/r-devel -- Vincent Goulet, Professeur agrégé École d'actuariat Université Laval, Québec [EMAIL PROTECTED] http://vgoulet.act.ulaval.ca ______________________________________________ R-devel@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
