Function PyArray_RemoveAxesInPlace

numpy/core/src/multiarray/shape.c:1005–1026

NUMPY_API * * Removes the axes flagged as True from the array, * modifying it in place. If an axis flagged for removal * has a shape entry bigger than one, this effectively selects * index zero for that axis. * * WARNING: If an axis flagged for removal has a shape equal to zero, * the array will point to invalid memory. The caller must * validate this! * If an

 * from a reduction result once its computation is complete.
 */
NPY_NO_EXPORT void
PyArray_RemoveAxesInPlace(PyArrayObject *arr, const npy_bool *flags)
{
    PyArrayObject_fields *fa = (PyArrayObject_fields *)arr;
    npy_intp *shape = fa->dimensions, *strides = fa->strides;
    int idim, ndim = fa->nd, idim_out = 0;

    /* Compress the dimensions and strides */
    for (idim = 0; idim < ndim; ++idim) {
        if (!flags[idim]) {
            shape[idim_out] = shape[idim];
            strides[idim_out] = strides[idim];
            ++idim_out;
        }
    }

    /* The final number of dimensions */
    fa->nd = idim_out;

    /* NOTE: This is only necessary if a dimension with size != 1 was removed */
    PyArray_UpdateFlags(arr, NPY_ARRAY_C_CONTIGUOUS | NPY_ARRAY_F_CONTIGUOUS);
}