"7" is an integer, but it's also a real. In R '?is' and '?is.integer' are clear that you're testing the class(es) of objects, not their values. I can't comment on the relationship with "S Programming"
hth Keith J <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] > This is really bothering me! In the Dr. Venables and Dr. Ripley's book "S > Programming" Page 105 > shows that >> c(is(10,"integer"),is(10.5,"integer")) > [1] T F > > But I try this in R 2.7.2 it shows >> c(is(10,"integer"),is(10.5,"integer")) > [1] FALSE FALSE > Does anyone know what is going on here? > > Appreciate, > Chunhao > > > > > Quoting Yihui Xie <[EMAIL PROTECTED]>: > >> Yes, everyone will agree "7" is an integer, but I don't think >> computers will agree too :-) R thinks it's a double-precision number, >> except when you explicitly specify it as an integer (say, >> as.integer()). >> >>> class(7) >> [1] "numeric" >> >>> is.double(7) >> [1] TRUE >> >> Regards, >> Yihui >> -- >> Yihui Xie <[EMAIL PROTECTED]> >> Phone: +86-(0)10-82509086 Fax: +86-(0)10-82509086 >> Mobile: +86-15810805877 >> Homepage: http://www.yihui.name >> School of Statistics, Room 1037, Mingde Main Building, >> Renmin University of China, Beijing, 100872, China >> >> >> >> On Wed, Sep 24, 2008 at 12:40 PM, <[EMAIL PROTECTED]> wrote: >>> Hi R users >>> Is there anything wrong in "is" function? (R 2.7.2) >>> I believe that everyone will agree that "7" is an integer, right? but >>> why R >>> shows 7 is not an integer >>> >>>> is.integer(7) >>> >>> [1] FALSE >>>> >>>> is(7,"integer") >>> >>> [1] FALSE >>>> >>>> is(as.integer(7), "integer") >>> >>> [1] TRUE >>> >>> Thank you very much in advance >>> Chunhao ______________________________________________ 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.
