R devel - Apr 2006 - is.numeric (NA + NA) is TRUE, should be FALSE (PR#8745)

Full_Name: c fillekes
Version: Version 2.2.1  (2005-12-20 r36812)
OS: Gentoo Linux kernel 2.6.12
Submission from: (NULL) (129.116.71.233)




"Not Available" is of course not a numeric: 
R
> is.numeric (NA)
[1] FALSE

But for some reason, all arithmetic operations on NA's are
in fact numeric, even if it's with other NA's.  

> is.numeric (NA+NA)
[1] TRUE
> is.numeric (NA^2)
[1] TRUE
> is.numeric (NA-NA)
[1] TRUE
> is.numeric (NA*NA)
[1] TRUE
> is.numeric (NA/NA)
[1] TRUE
>
This is not the expected thing.

On 4/4/2006 3:38 PM, cfillekes at gmail.com wrote:
> Full_Name: c fillekes
> Version: Version 2.2.1  (2005-12-20 r36812)
> OS: Gentoo Linux kernel 2.6.12
> Submission from: (NULL) (129.116.71.233)
> 
> 
> 
> 
> "Not Available" is of course not a numeric: 
> R
> 
>> is.numeric (NA)
> [1] FALSE
> 
> But for some reason, all arithmetic operations on NA's are
> in fact numeric, even if it's with other NA's.  
> 
> 
>> is.numeric (NA+NA)
> [1] TRUE
>> is.numeric (NA^2)
> [1] TRUE
>> is.numeric (NA-NA)
> [1] TRUE
>> is.numeric (NA*NA)
> [1] TRUE
>> is.numeric (NA/NA)
> [1] TRUE
>>
> 
> This is not the expected thing.
But it is the documented thing, so it is not a bug:

"'is.numeric' returns 'TRUE' if its argument is of mode
'"numeric"'
      (type '"double"' or type '"integer"')
and not a factor, and
      'FALSE' otherwise."

The value is irrelevant.  You probably want to use "is.numeric(x)
&&
all(is.finite(x))" to get the result you're expecting.

Duncan Murdoch

2006/4/4, cfillekes@gmail.com
<cfillekes@gmail.com>:
>
> Full_Name: c fillekes
> Version: Version 2.2.1  (2005-12-20 r36812)
> OS: Gentoo Linux kernel 2.6.12
> Submission from: (NULL) (129.116.71.233)
>
>
>
>
> "Not Available" is of course not a numeric:
> R
>
> > is.numeric (NA)
> [1] FALSE

In the help you can read:
"
 'NA' is a logical constant of length 1 which contains a missing
     value indicator.  'NA' can be freely coerced to any other vector
     type except raw.
"
And in fact:
> storage.mode(NA)
[1] "logical"
> storage.mode(NA+0)
[1] "double"
> storage.mode(as.numeric(NA))
[1] "double"
> storage.mode(as.character(NA))
[1] "character"

So in
NA+NA
the logical is automatically coerced to a numerical value, and
is.numericreturns TRUE, as expected.

But for some reason, all arithmetic operations on NA's
are
> in fact numeric, even if it's with other NA's.
>
>
> > is.numeric (NA+NA)
> [1] TRUE
> > is.numeric (NA^2)
> [1] TRUE
> > is.numeric (NA-NA)
> [1] TRUE
> > is.numeric (NA*NA)
> [1] TRUE
> > is.numeric (NA/NA)
> [1] TRUE
> >
>
> This is not the expected thing.

I think this is the expected thing.

______________________________________________
> R-devel@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>

Antonio, Fabio Di Narzo.

	[[alternative HTML version deleted]]