Merely convention. NULL == 2 <==> logical(0), that is, a logical vector of length 0. It makes sense (at least to me) that any(logical(0)) is FALSE, since no elements of the vector are TRUE. all(logical(0)) is TRUE since no elements of the vector are FALSE.
I think these are reasonable and fairly standard conventions, but even if you disagree, they are certainly not worth making a fuss over and certainly cannot be changed without breaking a lot of code, I'm sure. Bert Gunter Nonclinical Statistics 7-7374 -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Benilton Carvalho Sent: Wednesday, November 29, 2006 2:21 PM To: R-Mailingliste Subject: [R] tests for NULL objects Hi Everyone, After searching the subject and not being successful, I was wondering if any you could explain me the idea behind the following fact: all(NULL == 2) ## TRUE any(NULL == 2) ## FALSE Thanks a lot, Benilton -- Benilton Carvalho PhD Candidate Department of Biostatistics Johns Hopkins University ______________________________________________ R-help@stat.math.ethz.ch 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. ______________________________________________ R-help@stat.math.ethz.ch 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.
