[Rd] is.matrix
Wacek Kusnierczyk
Waclaw.Marcin.Kusnierczyk at idi.ntnu.no
Tue Nov 11 20:58:56 CET 2008
hadley wickham wrote:
> On Tue, Nov 11, 2008 at 1:42 PM, Wacek Kusnierczyk
> <Waclaw.Marcin.Kusnierczyk at idi.ntnu.no> 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)
>>
>
> I think you meant
> dim(x) <- c(3, 1)
>
> You created a 1 x 1 x 1 array.
>
i know, that's precisely what i wanted. this is a simple 3d structure,
yet is(x) reveals it is a matrix. that was the point.
some further observations:
x = as.list(1:2)
is(x)
# x is a list
dim(x) = 2
is.list(x)
# sure
is(x)
# not so sure any more -- a matrix?
vQ
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