R help - Jun 2015 - is.na for S4 object

Hi the list,

I have a variable y that is either NA or some S4 object. I would like to
know in which case I am, but it seems taht is.na does not work with S4
object, I get a warnings:

--- 8< ------------
setClass("myClass",slots=c(x="numeric"))
if(runif(1)>0.5){a <- new("myClass")}else{a <- NA}
is.na(a)
--- 8< ------------

Any solution?
Thanks 

Christophe




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On 06/04/2015 10:08 AM, cgenolin wrote:
> Hi the list,
>
> I have a variable y that is either NA or some S4 object. I would like to
> know in which case I am, but it seems taht is.na does not work with S4
> object, I get a warnings:
>
> --- 8< ------------
> setClass("myClass",slots=c(x="numeric"))
> if(runif(1)>0.5){a <- new("myClass")}else{a <- NA}
> is.na(a)
> --- 8< ------------
>
> Any solution?
getGeneric("is.na")

shows that it's an S4 generic, so implement a method

setMethod("is.na", "myClass", function(x) FALSE)

Martin
> Thanks
>
> Christophe
>
>
>
>
> --
> View this message in context:
http://r.789695.n4.nabble.com/is-na-for-S4-object-tp4708201.html
> Sent from the R help mailing list archive at Nabble.com.
>
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So easy!

Thanks a lot.



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>>>>> Martin Morgan <mtmorgan at fredhutch.org>
>>>>>     on Thu, 4 Jun 2015 10:33:37 -0700 writes:
    > On 06/04/2015 10:08 AM, cgenolin wrote:
    >> Hi the list,
    >> 
    >> I have a variable y that is either NA or some S4 object. I would
like to
    >> know in which case I am, but it seems taht is.na does not work with
S4
    >> object, I get a warnings:
    >> 
    >> --- 8< ------------
    >> setClass("myClass",slots=c(x="numeric"))
    >> if(runif(1)>0.5){a <- new("myClass")}else{a <-
NA}
    >> is.na(a)
    >> --- 8< ------------
    >> 
    >> Any solution?

    > getGeneric("is.na")

    > shows that it's an S4 generic, so implement a method

    > setMethod("is.na", "myClass", function(x) FALSE)

    > Martin

For the present special case though,  a more efficient solution would be
to use  isS4(.)  instead of  !is.na(.)

another Martin 


    >> Thanks
    >> Christophe