Re: [Rd] .Call - applying setAttrib(x, R_DimSymbol, s) to a matrix being an element of a list

From: Oleg Sklyar <osklyar_at_ebi.ac.uk>
Date: Thu 17 Mar 2005 - 01:34:53 GMT

Dear Simon,

> you gave us only a fragment of your code, so I can only guess what
the problem is:

> What is imgSize? The behavior you describe seems as if you re-using
the imgSize SEXP in all elements.
> AFAIR in your case setAttrib doesn't copy the value, so you need to
do so yourself (or alloc new dim array
> for each element).

Sorry, it is always a tradeoff - either to explain or put a relatively large code, which also uses non-standard libraries making the code difficult to read. imgSize values are reset in between: see the full code below. The SEXP pointer imgSize stays in tact, that's true, but its values are changed (the problem is, they are always the last in the row). I.e. if I have 3 images 40x20, 200x100 and 150x75 I will get three matrices of 150x75, but if I omit setAtrib and return vectors I get vectors of different length.

Oleg

SEXP load2DImages(SEXP fileNames) {

    int nFiles = LENGTH(fileNames);
    std::cout << "Loading " << nFiles << " files..." << std::endl;     // SEXP result = allocList(nFiles);
    SEXP result = allocVector(VECSXP, nFiles);     PROTECT(result);
    SEXP imgSize = allocVector(INTSXP, 2);     PROTECT(imgSize);

    TRGB2DImage::Pointer image;
    TRGB2DReader::Pointer reader = TRGB2DReader::New();
    TRGB2DImage::SizeType size;   
    TRGB2DImage::IndexType pixIndex;
    for (int i = 0; i < nFiles; i++) {
        try {
            char *filename = CHAR(asChar(VECTOR_ELT(fileNames, i)));
            std::cout << std::endl << "Loading image file " << filename 
<< "... ";
            reader->SetFileName(filename);
            reader->Update();
            image = reader->GetOutput();
        } catch(...) {
            std::cout << "failed!";
            continue;
        }
        std::cout << std::endl;
        size = image->GetLargestPossibleRegion().GetSize();
        INTEGER(imgSize)[0] = size[1];
        INTEGER(imgSize)[1] = size[0];
        std::cout << size[0] << " x " << size[1] << std::endl;
        SET_VECTOR_ELT(result, i, allocVector(INTSXP, size[0] * size[1]));
        SEXP element = VECTOR_ELT(result, i);
        for (int ix = 0; ix < size[0]; ix++) {
            pixIndex[0] = ix;
            for (int iy = 0; iy < size[1]; iy++) {
                pixIndex[1] = iy;
                INTEGER(element)[size[1] * ix + iy] = 
getIntRGBColour(image->GetPixel(pixIndex));
            }
        }
        setAttrib(element, R_DimSymbol, imgSize);
    }
    UNPROTECT(2);
    if (nFiles == 1)

        return VECTOR_ELT(result, 0);
    else

        return result;
}

Dr Oleg Sklyar
European Bioinformatics Institute
Wellcome Trust Genome Campus
Hinxton, Cambridge, CB10 1SD
England
phone/fax +44(0)1223 49 4478/4468
e-mail osklyar@ebi.ac.uk

Simon Urbanek wrote:

> Oleg,
>
> you gave us only a fragment of your code, so I can only guess what the 
> problem is:
>
> On Mar 16, 2005, at 12:40 PM, Oleg Sklyar wrote:
>
>> // converting element into a matrix
>> setAttrib(element, R_DimSymbol, imgSize);
>
>
> What is imgSize? The behavior you describe seems as if you re-using 
> the imgSize SEXP in all elements. AFAIR in your case setAttrib doesn't 
> copy the value, so you need to do so yourself (or alloc new dim array 
> for each element).
>
> Cheers,
> Simon
>
>
>

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https://stat.ethz.ch/mailman/listinfo/r-devel Received on Thu Mar 17 12:36:56 2005

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