Matt’s blog

This question was asked on the Scipy mailing-list last year (well, one week ago). Nathan Bell proposed a skeleton that I used to create an out typemap for SWIG.

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%typemap(out) std::vector<double> {
    int length = $1.size();
    $result = PyArray_FromDims(1, &amp;length, PyArray_DOUBLE);
    memcpy(PyArray_DATA($result),&amp;((*(&amp;$1))[0]),sizeof(double)*length);
}
</double>

This typemap uses obviously Numpy, so don’t forget to initialize the module and to import it. Then there is a strange instruction in memcpy. &((*(&$1))[0]) takes the address of the array of the vector, but as it is wrapped by SWIG, one has to get to the std::vector by dereferencing the SWIG wrapper. Then one can get the first element in the vector and take the address.

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