On Mon, Nov 10, 2008 at 4:17 PM, Wacek Kusnierczyk <[EMAIL PROTECTED]> wrote: > Gabor Grothendieck wrote: >> Certainly this has been recognized as a potential problem: >> >> http://developer.r-project.org/nonstandard-eval.pdf >> >> however, it is convenient when you are performing >> an analysis and entering commands directly as opposed >> to writing a program although possibly the potential ambiguities >> overshadow the convenience. >> > > in most cases, i do not see why one could not use a string literal > passed by value instead of having an expression deparsed within the > function, which may lead to confusing behaviour. this would give much > more consistent and predictable code. this has nothing to do with the > evaluation mechanism, which can still be lazy. > > > > in the case of subset, i do not really see how this design might be > helpful, but it's easy to see how it can be harmful, examples have just
I think the thrust of your comments were already made by reference. Regarding the convenience it occurs in expressions like this: iris2 <- subset(iris, select = - Species) to create a data frame without the Species column. Perhaps this would have better been done by allowing an optional formula for the select clause: iris2 <- subset(iris, select = ~ - Species) but I think R is stuck with what it has due to compatibility and the large base of users yet its still possible to add functions in packages or new functions to R so a new variant of subset would be possible in which case one could decide to use the new function in place of the old one. ______________________________________________ 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.