Function PyUFunc_Reduce

numpy/core/src/umath/ufunc_object.c:3034–3088

* The implementation of the reduction operators with the new iterator * turned into a bit of a long function here, but I think the design * of this part needs to be changed to be more like einsum, so it may * not be worth refactoring it too much. Consider this timing: * * >>> a = arange(10000) * * >>> timeit sum(a) * 10000 loops, best of 3: 17 us per loop * * >>> timeit einsum("i->",a)

 * this function does not validate them.
 */
static PyArrayObject *
PyUFunc_Reduce(PyUFuncObject *ufunc,
        PyArrayObject *arr, PyArrayObject *out,
        int naxes, int *axes, PyArray_DTypeMeta *signature[3], int keepdims,
        PyObject *initial, PyArrayObject *wheremask)
{
    int iaxes, ndim;
    npy_bool axis_flags[NPY_MAXDIMS];

    const char *ufunc_name = ufunc_get_name_cstr(ufunc);
    /* These parameters come from a TLS global */
    int buffersize = 0, errormask = 0;

    NPY_UF_DBG_PRINT1("\nEvaluating ufunc %s.reduce\n", ufunc_name);

    ndim = PyArray_NDIM(arr);

    /* Create an array of flags for reduction */
    memset(axis_flags, 0, ndim);
    for (iaxes = 0; iaxes < naxes; ++iaxes) {
        int axis = axes[iaxes];
        if (axis_flags[axis]) {
            PyErr_SetString(PyExc_ValueError,
                    "duplicate value in 'axis'");
            return NULL;
        }
        axis_flags[axis] = 1;
    }

    if (_get_bufsize_errmask(NULL, "reduce", &buffersize, &errormask) < 0) {
        return NULL;
    }

    PyArray_Descr *descrs[3];
    PyArrayMethodObject *ufuncimpl = reducelike_promote_and_resolve(ufunc,
            arr, out, signature, NPY_FALSE, descrs, NPY_UNSAFE_CASTING, "reduce");
    if (ufuncimpl == NULL) {
        return NULL;
    }

    PyArrayMethod_Context context = {
        .caller = (PyObject *)ufunc,
        .method = ufuncimpl,
        .descriptors = descrs,
    };

    PyArrayObject *result = PyUFunc_ReduceWrapper(&context,
            arr, out, wheremask, axis_flags, keepdims,
            initial, reduce_loop, buffersize, ufunc_name, errormask);

    for (int i = 0; i < 3; i++) {
        Py_DECREF(descrs[i]);
    }
    return result;
}


static PyObject *