[Rd] is.matrix

[Wacek Kusnierczyk]

Wacek Kusnierczyk wrote:
> hadley wickham wrote:
>   
>>> |  is.matrix| returns |TRUE| if |x| is a matrix and has a |dim <dim.html>|
>>> attribute of length 2) and |FALSE| otherwise
>>>     
>>>       
>> That's confusing!  In what situations is x a matrix but does not have
>> a dim attribute?
>>
>>   
>>     
>
> x = matrix(1,1,1)
> dim(x) = c(1,1,1)
> is.matrix(x)
> # no
> is("matrix", x)
> # no
> is(x)
> # hm...
>
> following the last, there would be a situation in which an object is a
> matrix (per is(...)) and has a dim attribute of length != 2, but is a
>   
but is *not*

> matrix (per is.matrix(...) and is("matrix", ...), consistently with the
> docs).
>
> (the redundant "vector" in is(x) could probably be removed?)
>
> vQ
>
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