[R] bug or bizarre feature?

[Henrique Dallazuanna]

Dim argument must be a integer, see the return of:

as.integer(slope*xdim)

Try this:

udim <- ceiling(max(slope*xdim,5))

On Mon, Nov 30, 2009 at 5:15 PM, Rupert Mazzucco <rmaz at gmx.net> wrote:
> Hello,
>
> I'm running into a very strange problem:
>
>> xrange <- c(-2.5,2.5)
>> xdim <- 100
>> mobility <- 0.1
>> slope <- 1.16
>> urange <- slope*xrange
>>         udim <- max(slope*xdim,5)
>>         du <- (urange[2]-urange[1])/udim
>>         uvec <- urange[1]+(1:udim-0.5)*du
>>         # type dependent weight function
>>         ckern <- array(0,dim=c(udim,udim))
>>         diag(ckern) = wfun(uvec,slope,mobility)
> Error in `diag<-`(`*tmp*`, value = c(0.992300064325398, 0.990746129315703,  :
>  replacement diagonal has wrong length
>
> It turns out that the array ckern has the wrong size for some reason.
> Instead of 116x116, it is only 115x115.
>
>> udim
> [1] 116
>> length(uvec)
> [1] 116
>> length(wfun(uvec,slope,mobility))
> [1] 116
>> dim(ckern)
> [1] 115 115
>
> The "taint" or whatever that is, is even transferable
>
>> n <- udim
>> n
> [1] 116
>> ckern <- array(0,dim=c(n,n))
>> dim(ckern)
> [1] 115 115
>> m <- n
>> m
> [1] 116
>> ckern <- array(0,dim=c(m,m))
>> dim(ckern)
> [1] 115 115
>
> But when I set it explicitly, it does what it should:
>
>> n <- 116
>> n
> [1] 116
>> ckern <- array(0,dim=c(n,n))
>> dim(ckern)
> [1] 116 116
>
> Note that the funny behavior seems to be peculiar to this one value of slope <- 1.16,
> many others work fine, e.g.
>
>> slope <- 1.08
>> urange <- slope*xrange
>>         udim <- max(slope*xdim,5)
>>         du <- (urange[2]-urange[1])/udim
>>         uvec <- urange[1]+(1:udim-0.5)*du
>>         # type dependent weight function
>>         ckern <- array(0,dim=c(udim,udim))
>>         diag(ckern) = wfun(uvec,slope,mobility)
>> dim(ckern)
> [1] 108 108
>
> This is R 2.10.0, but also happened in 2.8.0. Can anybody tell me what
> is going on here, and how I can get my array to be the right size?
>
> Thanks,
> Rupert
>
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>



-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O