R devel - Sep 2009 - buglet in is.na?

Hi
the following example I think demonstrates the
inconsistency
> f<-function(x) x
> length(f)
[1] 1
> is.na(f)
[1] FALSE
Warning message:
In is.na(f) : is.na() applied to non-(list or vector) of type 'closure'

The documentation states:
Arguments
x       an R object to be tested.
value   a suitable index vector for use with x.

And nowhere in the details was it implied (to me anyway) that x could
not be a function
or anything else in R for that matter. Did I miss something?

Nicholas

On 9/30/2009 2:29 PM, Nicholas Lewin-Koh wrote:
> Hi
> the following example I think demonstrates the inconsistency
>> f<-function(x) x
>> length(f)
> [1] 1
>> is.na(f)
> [1] FALSE
> Warning message:
> In is.na(f) : is.na() applied to non-(list or vector) of type
'closure'
As the error message says, closures aren't vectors.  However, they do 
have a length.
> The documentation states:
> Arguments
> x       an R object to be tested.
> value   a suitable index vector for use with x.
> 
> And nowhere in the details was it implied (to me anyway) that x could
> not be a function
> or anything else in R for that matter. Did I miss something?
This might be an omission from the docs, but it did say pretty clearly 
in the warning message that x needs to be a vector.  So it's not a bug.

The source for the docs is in

https://svn.r-project.org/R/trunk/src/library/base/man/NA.rd

If you can think of a way to make it clearer, and you think this is the 
sort of error someone would not understand given the warning message, 
please submit a patch.

Duncan Murdoch

Nicholas Lewin-Koh wrote:
> Hi
> the following example I think demonstrates the inconsistency
>> f<-function(x) x
>> length(f)
> [1] 1
>> is.na(f)
> [1] FALSE
> Warning message:
> In is.na(f) : is.na() applied to non-(list or vector) of type
'closure'
> 
> The documentation states:
> Arguments
> x       an R object to be tested.
> value   a suitable index vector for use with x.
> 
> And nowhere in the details was it implied (to me anyway) that x could
> not be a function
> or anything else in R for that matter. Did I miss something?
> 
Well, it's just a warning which you get whenever you apply is.na to 
things that cannot logically be NA, e.g.

 > is.na(.GlobalEnv)
[1] FALSE FALSE
Warning message:
In is.na(.GlobalEnv) :
   is.na() applied to non-(list or vector) of type 'environment'
 > is.na(quote(a))
[1] FALSE
Warning message:
In is.na(quote(a)) :
   is.na() applied to non-(list or vector) of type 'symbol'
 > is.na(quote(`NA`))
[1] FALSE
Warning message:
In is.na(quote(`NA`)) :
   is.na() applied to non-(list or vector) of type 'symbol'
 > is.na(is.na)
[1] FALSE
Warning message:
In is.na(is.na) : is.na() applied to non-(list or vector) of type
'builtin'

I suppose the documentation could be more explicit about it, but where's 
the need?

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