[Rd] bug or feature? (PR#4150)

John Fox jfox at mcmaster.ca
Sat Sep 13 10:01:59 MEST 2003

Dear Axel,

At 01:37 PM 9/13/2003 +0200, axel.benz at iao.fhg.de wrote:
>Full_Name: Axel Benz
>Version: 1.7.1
>OS: Windows
>Submission from: (NULL) (
>This feature seems to be a basic bug:
> > 1=="1"
>[1] TRUE
> > as.numeric(1)=="1"
>[1] TRUE
> > as.numeric(1)==as.character("1")
>[1] TRUE
>isn't it necessary to distinguish beteen numbers and characters??

Coercion to a common mode takes place in many contexts; for example:

         > 1 & TRUE
         [1] TRUE

To distinguish between numbers and characters you can, of course, use the 
predicates is.numeric() and is.character(), or test that the mode() of the 
arguments is the same.

John Fox
Department of Sociology
McMaster University
Hamilton, Ontario, Canada L8S 4M4
email: jfox at mcmaster.ca
phone: 905-525-9140x23604
web: www.socsci.mcmaster.ca/jfox

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