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I have a little project that works beautifully with SWIG. In particular, some of my functions return std::vector s, which get translated to tuples in Python. Now, I do a lot of numerics, so I just have SWIG convert these to numpy arrays after they're returned from the c++ code. To do this, I use something like the following in SWIG. %feature("pythonappend") My::Cool::Namespace::Data() const %{ if isinstance(val, tuple) : val = numpy.array(val) %} (Actually, there are several functions named Data, some of which return floats, which is why I check that val is actually a tuple.) This works just beautifully. But, I'd also like to use the -builtin flag that's now available. Calls to these Data functions are rare and mostly interactive, so their slowness is not a problem, but there are other slow loops that speed up significantly with the builtin option. The problem is that when I use that flag, the pythonappend feature is silently ignored. Now, Data just returns a tuple again. Is there any way I could still return numpy arrays? I tried using typemaps, but it turned into a giant mess. Edit: Borealid has answered the question very nicely. Just for completeness, I include a couple related but subtly different typemaps that I need because I return by const reference and I use vectors of vectors (don't start!). These are different enough that I wouldn't want anyone else stumbling around trying to figure out the minor differences. %typemap(out) std::vector<int>& { npy_intp result_size = $1->size(); npy_intp dims[1] = { result_size }; PyArrayObject* npy_arr = (PyArrayObject*)PyArray_SimpleNew(1, dims, NPY_INT); int* dat = (int*) PyArray_DATA(npy_arr); for (size_t i = 0; i < result_size; ++i) { dat[i] = (*$1)[i]; } $result = PyArray_Return(npy_arr); } %typemap(out) std::vector<std::vector<int> >& { np

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