[R] how to check if an attribute exists

[Nick Matzke]

Oh wait, this basically does it:

 > if ("a" %in% attributes(z)$names)
+ print(TRUE)
[1] TRUE

(but there may be a better way)

Cheers!
Nick

On 2/2/11 7:20 PM, Nick Matzke wrote:
> I am dealing with an object that sometimes has a certain
> attribute, sometimes doesn't. How do I check for this?
> "exists" doesn't work...
>
> =======================
>  > z=c()
>  > z$a = c("c", "d", "f")
>  > z
> $a
> [1] "c" "d" "f"
>
>  > exists("z")
> [1] TRUE
>
>  > exists("z$a")
> [1] FALSE
> =======================
>
> ...basically, I want something that returns TRUE if the $a
> exists in z...
>
> Thanks!
> Nick
>
>
>

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====================================================
Nicholas J. Matzke
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