On Aug 23, 2010, at 5:51 PM, ivo welch wrote:
quizz---what does this produce? d=data.frame( a=1:1000, b=2001:3000, z= 5001:6000 ) attach(d); c <- (a+b)>25; detach(d) 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...
You have created a perfect example for why it is a bad idea to attach data.frames.
?attach # yes, I am yet again saying: "read the help page..." ... especially the 4th paragraph of the Details section. -- David. David Winsemius, MD West Hartford, CT ______________________________________________ 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.
