[R] Variable Wildcard Value

[Romain Francois]

Hi,

Since you insist, here is something that I think matches the 
specifications :

wildcard <- function( ) structure( NULL, class = "wildcard" )
Ops.wildcard <- function (e1, e2){
    if (nargs() == 1L)
        return( e1 )
    result <- switch(.Generic,
        `<` = , `>` = , `==` = ,
        `<=` = , `>=` = TRUE, `!=` = FALSE)
    result
}
is.na.wildcard <- function( x ) FALSE


 > w == 1
[1] TRUE
 > w == "peanut butter"
[1] TRUE
 > is.na( w )
[1] FALSE
 > "peanut butter" == w
[1] TRUE
 > w == w
[1] TRUE
 > w != w
[1] FALSE

# Is negation of a wildcard also a wildcard, or should it be a bizarro 
wildcard ?
 > (!w) == 2
[1] TRUE


Not really sure how this could be useful though, and would also be 
interested in Francis end game.

Romain


Patrick Burns wrote:
> I would be truly amazed if the answer were "yes".
>
> I find this the most fascinating question on R-help
> for a long time, maybe ever.  Can you tell us what
> you have in mind and what your ultimate purpose is?
>
> Patrick Burns
> patrick at burns-stat.com
> +44 (0)20 8525 0696
> http://www.burns-stat.com
> (home of "The R Inferno" and "A Guide for the Unwilling S User")
>
> Francis Smart wrote:
>> Is there a wildcard value for vector values in r?
>>
>> For instance:
>>
>>  
>>> M <- *wildcard
>>>     
>>
>>  
>>> (M==1)
>>>     
>> TRUE
>>
>>  
>>> (M=="peanut butter")
>>>     
>> TRUE
>>
>>  
>>> is.na(M)
>>>     
>> FALSE
>>
>> thanks,
>> Francis
>>
>>
>
> ______________________________________________
> R-help at 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.
>
>
>


-- 
Romain Francois
Independent R Consultant
+33(0) 6 28 91 30 30
http://romainfrancois.blog.free.fr