[Rd] Matrix dimnames crash (PR#13361)

[Prof Brian Ripley]

On Wed, 3 Dec 2008, William Dunlap wrote:

> Brian,
>   Your change to src/main/attrib.c:dimnamesgets(),
> --- attrib.c    (revision 47045)
> +++ attrib.c    (working copy)
> @@ -857,6 +857,9 @@
>        UNPROTECT(1);
>        PROTECT(val = newval);
>     }
> +    if (k != length(val))
> +       error(_("length of 'dimnames' [%d] must match that of 'dims'
> [%d]"),
> +             length(val), k);
>     for (i = 0; i < k; i++) {
>        SEXP _this = VECTOR_ELT(val, i);
>        if (_this != R_NilValue) {
> results in array() and matrix() treating dimnames=list() differently
> and I think they ought to act the same when feasible.
> Also, the error message is not really the right one, as the length
> of the dimnames handed to the array() or matrix() function does not
> have to be the length of dim - a short one gets padded with NULL's.
> (I don't know if this padding is the best thing to do -- R does it
> and S+ does not -- and I think it generally reflects user error.)

Not always: setting dimnames(A)[[1]] is the crux example.

> E.g., in R:
>
>> f<-function(dimnames){
>    mat<-try(matrix(1:6,nrow=2,dimnames=dimnames), silent=TRUE)
>    arr<-try(array(1:6,dim=c(2,3),dimnames=dimnames), silent=TRUE)
>    list(matrix=mat, array=arr, identical=identical(mat, arr))
> }
>
>> f(dimnames=NULL)
> $matrix
>     [,1] [,2] [,3]
> [1,]    1    3    5
> [2,]    2    4    6
>
> $array
>     [,1] [,2] [,3]
> [1,]    1    3    5
> [2,]    2    4    6
>
> $identical
> [1] TRUE
>
>> f(dimnames=list())
> $matrix
> [1] "Error in matrix(1:6, nrow = 2, dimnames = dimnames) : \n  length of
> 'dimnames' [0] must match that of 'dims' [2]\n"
> attr(,"class")
> [1] "try-error"
>
> $array
>     [,1] [,2] [,3]
> [1,]    1    3    5
> [2,]    2    4    6
>
> $identical
> [1] FALSE
>
>> f(dimnames=list(Row=LETTERS[24:25])) # short dimnames
> $matrix
>
> Row [,1] [,2] [,3]
>  X    1    3    5
>  Y    2    4    6
>
> $array
>
> Row [,1] [,2] [,3]
>  X    1    3    5
>  Y    2    4    6
>
> $identical
> [1] TRUE
>
>
> The following change to src/main/array.c makes array() and matrix()
> treat dimnames=list() in the same way (equivalent to dimnames=NULL.

which is not obvious to me is correct.

> --- array.c     (revision 47047)
> +++ array.c     (working copy)
> @@ -152,7 +152,7 @@
>            ;
>        }
>     }
> -    if(!isNull(dimnames)) ans = dimnamesgets(ans, dimnames);
> +    if(!isNull(dimnames) && length(dimnames)>0) ans = dimnamesgets(ans,
> dimnames);
>     UNPROTECT(1);
>     return ans;
> }
>
> The change to attrib.c:dimnamesgets() is fine: this change to
> array.c:do_matrix just avoids the call.
>
> Bill Dunlap
> TIBCO Software Inc - Spotfire Division
> wdunlap tibco.com
>
>> -----Original Message-----
>> From: r-devel-bounces at r-project.org
>> [mailto:r-devel-bounces at r-project.org] On Behalf Of Prof Brian Ripley
>> Sent: Wednesday, December 03, 2008 9:14 AM
>> To: arnima at u.washington.edu
>> Cc: R-bugs at r-project.org; r-devel at stat.math.ethz.ch
>> Subject: Re: [Rd] Matrix dimnames crash (PR#13361)
>>
>> On Wed, 3 Dec 2008, arnima at u.washington.edu wrote:
>>
>>> In Windows XP, the matrix() function crashes the program
>> when 'dimnames'
>>> is an empty list:
>>>
>>>   matrix(1:4, nrow=2, dimnames=list())
>>>   # R has encountered a problem and needs to close ...
>>>
>>> This bug is specific to WinXP, as Linux64 handles this
>> situation more
>>> gracefully:
>>>
>>>   matrix(1:4, nrow=2, dimnames=list())
>>>   Error in matrix(1:4, nrow = 2, dimnames = list()) :
>>>     invalid type (environment) for 'dimnames' (must be a vector)
>>
>> Actually no (the reported type is wrong, and my x86_64 Linux
>> system also
>> crashes).
>>
>> This case slips though the error-checking, and I've added a
>> final error
>> check that will catch it in R-patched.
>>
>> Thank you for the report.
>>
>>>
>>> Thanks,
>>> Arni
>>>
>>> R 2.8.0-patched on WinXP
>>>
>>> ______________________________________________
>>> R-devel at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>>
>>
>> --
>> Brian D. Ripley,                  ripley at stats.ox.ac.uk
>> Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
>> University of Oxford,             Tel:  +44 1865 272861 (self)
>> 1 South Parks Road,                     +44 1865 272866 (PA)
>> Oxford OX1 3TG, UK                Fax:  +44 1865 272595
>>
>> ______________________________________________
>> R-devel at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>
>

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595