Function PyArray_IterAllButAxis

numpy/core/src/multiarray/iterators.c:282–334

NUMPY_API * Get Iterator that iterates over all but one axis (don't use this with * PyArray_ITER_GOTO1D). The axis will be over-written if negative * with the axis having the smallest stride. */

 * with the axis having the smallest stride.
 */
NPY_NO_EXPORT PyObject *
PyArray_IterAllButAxis(PyObject *obj, int *inaxis)
{
    PyArrayObject *arr;
    PyArrayIterObject *it;
    int axis;

    if (!PyArray_Check(obj)) {
        PyErr_SetString(PyExc_ValueError,
                "Numpy IterAllButAxis requires an ndarray");
        return NULL;
    }
    arr = (PyArrayObject *)obj;

    it = (PyArrayIterObject *)PyArray_IterNew((PyObject *)arr);
    if (it == NULL) {
        return NULL;
    }
    if (PyArray_NDIM(arr)==0) {
        return (PyObject *)it;
    }
    if (*inaxis < 0) {
        int i, minaxis = 0;
        npy_intp minstride = 0;
        i = 0;
        while (minstride == 0 && i < PyArray_NDIM(arr)) {
            minstride = PyArray_STRIDE(arr,i);
            i++;
        }
        for (i = 1; i < PyArray_NDIM(arr); i++) {
            if (PyArray_STRIDE(arr,i) > 0 &&
                PyArray_STRIDE(arr, i) < minstride) {
                minaxis = i;
                minstride = PyArray_STRIDE(arr,i);
            }
        }
        *inaxis = minaxis;
    }
    axis = *inaxis;
    /* adjust so that will not iterate over axis */
    it->contiguous = 0;
    if (it->size != 0) {
        it->size /= PyArray_DIM(arr,axis);
    }
    it->dims_m1[axis] = 0;
    it->backstrides[axis] = 0;

    /*
     * (won't fix factors so don't use
     * PyArray_ITER_GOTO1D with this iterator)
     */
    return (PyObject *)it;
}

/*NUMPY_API
 * Adjusts previously broadcasted iterators so that the axis with