On Dec 8, 2007, at 1:02 AM, Joe W. Byers wrote: > In a post on R-devel, Prof Ripley add the following comment > | > BTW, 1:dim(names)[1] is dangerous: it could be 1:0. That was the > | > motivation for seq_len. > > I use the dim(names)[1] and dim(x)[2] along with length(x) with > varying > levels of frustration depending on the object which I am trying to get > the dimensions. I found the reference to seq_len interesting since it > is a function that I have never seen (probably just missed it reading > the docs). > > I was hoping someone could expand on the benefits of seq_len.
I think that example says it all. But in simpler form, suppose x is a vector, and you want to produce a regular sequence of integers of the same length. What should happen i the vector x has length 0? Here's the output of the two commands. x<-numeric(0) > y<-length(x) > y [1] 0 > 1:y [1] 1 0 > seq_len(y) integer(0) Other than treating the edge case correctly, the only other advantage of seq_len, that I am aware of, is that it is faster. Not sure how often that ends up mattering though. > Happy Holidays > Joe > Haris Skiadas Department of Mathematics and Computer Science Hanover College ______________________________________________ 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.
