I assume it's to return the vectors in their original order. -- Bert
Bert Gunter "Data is not information. Information is not knowledge. And knowledge is certainly not wisdom." -- Clifford Stoll On Wed, Sep 16, 2015 at 2:10 PM, David Winsemius <dwinsem...@comcast.net> wrote: > > On Sep 15, 2015, at 7:20 PM, Charles C. Berry wrote: > >> On Tue, 15 Sep 2015, Bert Gunter wrote: >> >>> Thanks to both Davids. >>> >>> I realize that these things are often a matter of aesthetics -- and >>> hence have little rational justification -- but I agree with The Other >>> David: eval(parse) seems to me to violate R's soul( it makes R a macro >>> language instead of a functional one). >>> >>> However, mapply(... switch) effectively loops through the frame row by >>> row. Aesthetically, I like it; but it seems inefficient. If there are >>> e.g. 1e6 rows in say 10 categories, I think Jeff's approach should do >>> much better. I'll try to generate some actual data to see unless >>> someone else beats me to it. >> >> Use mapply like this on large problems: >> >> unsplit( >> mapply( >> function(x,z) eval( x, list( y=z )), >> expression( A=y*2, B=y+3, C=sqrt(y) ), >> split( dat$Flow, dat$ASB ), >> SIMPLIFY=FALSE), >> dat$ASB) >> > > Seems unnecessarily complex, but definitely elegant. Was there a reason it > was not just: > > mapply( > function(x,z) eval( x, list( y=z )), > expression(A= y*2, B=y+3, C=sqrt(y) ), > split( dat$Flow, dat$ASB ) > ) > > Also readers should note that the names in that expression vector are quite > arbitrary at the moment. The only association is via the order. I don't > suppose someone wants to take on the challenge of matching the names of the > expression vector with the names of returned split components? > > >> Chuck > > David Winsemius > Alameda, CA, USA > ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
