Function array_shape_set

numpy/core/src/multiarray/getset.c:47–102

static int
array_shape_set(PyArrayObject *self, PyObject *val, void* NPY_UNUSED(ignored))
{
    int nd;
    PyArrayObject *ret;

    if (val == NULL) {
        PyErr_SetString(PyExc_AttributeError,
                "Cannot delete array shape");
        return -1;
    }
    /* Assumes C-order */
    ret = (PyArrayObject *)PyArray_Reshape(self, val);
    if (ret == NULL) {
        return -1;
    }
    if (PyArray_DATA(ret) != PyArray_DATA(self)) {
        Py_DECREF(ret);
        PyErr_SetString(PyExc_AttributeError,
                        "Incompatible shape for in-place modification. Use "
                        "`.reshape()` to make a copy with the desired shape.");
        return -1;
    }

    nd = PyArray_NDIM(ret);
    if (nd > 0) {
        /* create new dimensions and strides */
        npy_intp *_dimensions = npy_alloc_cache_dim(2 * nd);
        if (_dimensions == NULL) {
            Py_DECREF(ret);
            PyErr_NoMemory();
            return -1;
        }
        /* Free old dimensions and strides */
        npy_free_cache_dim_array(self);
        ((PyArrayObject_fields *)self)->nd = nd;
        ((PyArrayObject_fields *)self)->dimensions = _dimensions; 
        ((PyArrayObject_fields *)self)->strides = _dimensions + nd;

        if (nd) {
            memcpy(PyArray_DIMS(self), PyArray_DIMS(ret), nd*sizeof(npy_intp));
            memcpy(PyArray_STRIDES(self), PyArray_STRIDES(ret), nd*sizeof(npy_intp));
        }
    }
    else {
        /* Free old dimensions and strides */
        npy_free_cache_dim_array(self);        
        ((PyArrayObject_fields *)self)->nd = 0;
        ((PyArrayObject_fields *)self)->dimensions = NULL;
        ((PyArrayObject_fields *)self)->strides = NULL;
    }

    Py_DECREF(ret);
    PyArray_UpdateFlags(self, NPY_ARRAY_C_CONTIGUOUS | NPY_ARRAY_F_CONTIGUOUS);
    return 0;
}