On Mon, 2010-08-23 at 17:51 -0400, ivo welch wrote: > quizz---what does this produce?
Henrique has provided an answer to the question, but... > d=data.frame( a=1:1000, b=2001:3000, z= 5001:6000 ) > attach(d); c <- (a+b)>25; detach(d) ...this is ugly and will potentially catch you out one day if you forget to detach. These three calls can be achieved using a single with() : c <- with(d, (a + b) > 25) And the version you wanted: attach(d); d$c <- (a+b)>25; detach(d) can be done using within(): d <- within(d, c <- (a + b) > 25) and with the latter, the intention is pretty clear. HTH G > d= subset(d, TRUE, select=c( a, b, c )) > > yes, I know I have made a mistake, in that the code does not do what I > presumably would have wanted. it does seem like unexpected behavior, > though, without an error. there probably is some reason why this does > not ring an alarm bell... > > /iaw > ---- > Ivo Welch (ivo.we...@brown.edu, ivo.we...@gmail.com) > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. -- %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% 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-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
