[R] Bug in "is" ?

[ctu at bigred.unl.edu]

Thank you for all of you. Intuitively, 7 is an integer for people who  
live in this planet. It is just very difficult for me to believe that  
R does not think 7 is an integer but 7L is.
> is.integer(7)  # R 2.7.2
[1] FALSE
Thus, based on Martin's comments, I try it again on the S-PLUS 8.0 and  
it shows
> is.integer(7)   # S-PLUS 8.0
[1] T

Hopefully, someday and someone will fix it therefore, R users don't  
need to use as.integer(7) to tell R that 7 is an integer.

Thanks again
Chunhao


Quoting Martin Maechler <maechler at stat.math.ethz.ch>:

>>>>>> "KJ" == Keith Jewell <k.jewell at campden.co.uk>
>>>>>>     on Wed, 24 Sep 2008 09:46:08 +0100 writes:
>
>     KJ> "7" is an integer, but it's also a real.
>     KJ> In R '?is'  and '?is.integer' are clear that you're testing   
> the class(es) of
>     KJ> objects, not their values.
>     KJ> I can't comment on the relationship with "S Programming"
>
> I can:
>
> In S, and S-plus upto version 3.4,
> numeric constants such as '7' where  "double" as they are in R.
>
> Then in S-plus 5.1, they became "integer",
> and there were tools so users could change all(!!) their S
> scripts to use '7.' instead of '7' in all places where numeric
> constants were seen, in order to keep behavior back compatible.
>
> R never made such a step (backwards ;-), and never will,
> notably since in R we had introduced the explicit long (= long
> integer) constants, using the 'L' suffix,
> i.e.,  7L is "integer"
>         7 is "double"
>
> Note however that for both, is.numeric(.) is fulfilled and
> class(.) and mode(.) return "numeric".
> Only typeof(.), storage.mode(.)  or  str(.)
> (or functions building on these) tell you the difference.
>
> Martin Maechler, ETH Zurich and R core team
>
> [And, yes, if you think further and are wondering:
>  If we'd design things from scratch, we would only have S4
>  classes and "double" would be a proper class and
>  "numeric" would be the class union of {"integer", "double"}
> ]
>
>
>     KJ> <ctu at bigred.unl.edu> wrote in message
>     KJ> news:20080924000503.1fsyrqf6zokk40kg at wm-imp-1.unl.edu...
>     >> 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 <xieyihui at gmail.com>:
>     >>
>     >>> 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 <xieyihui at gmail.com>
>     >>> 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,  <ctu at bigred.unl.edu> 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
>
>     KJ> ______________________________________________
>     KJ> R-help at r-project.org mailing list
>     KJ> https://stat.ethz.ch/mailman/listinfo/r-help
>     KJ> PLEASE do read the posting guide   
> http://www.R-project.org/posting-guide.html
>     KJ> and provide commented, minimal, self-contained, reproducible code.
>
> ______________________________________________
> R-help at r-project.org mailing list
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>