Function PyArray_Newshape

numpy/core/src/multiarray/shape.c:200–291

NUMPY_API * New shape for an array */

 * New shape for an array
 */
NPY_NO_EXPORT PyObject *
PyArray_Newshape(PyArrayObject *self, PyArray_Dims *newdims,
                 NPY_ORDER order)
{
    npy_intp i;
    npy_intp *dimensions = newdims->ptr;
    PyArrayObject *ret;
    int ndim = newdims->len;
    npy_bool same;
    npy_intp *strides = NULL;
    npy_intp newstrides[NPY_MAXDIMS];
    int flags;

    if (order == NPY_ANYORDER) {
        order = PyArray_ISFORTRAN(self) ? NPY_FORTRANORDER : NPY_CORDER;
    }
    else if (order == NPY_KEEPORDER) {
        PyErr_SetString(PyExc_ValueError,
                "order 'K' is not permitted for reshaping");
        return NULL;
    }
    /*  Quick check to make sure anything actually needs to be done */
    if (ndim == PyArray_NDIM(self)) {
        same = NPY_TRUE;
        i = 0;
        while (same && i < ndim) {
            if (PyArray_DIM(self,i) != dimensions[i]) {
                same=NPY_FALSE;
            }
            i++;
        }
        if (same) {
            return PyArray_View(self, NULL, NULL);
        }
    }

    /*
     * fix any -1 dimensions and check new-dimensions against old size
     */
    if (_fix_unknown_dimension(newdims, self) < 0) {
        return NULL;
    }
    /*
     * sometimes we have to create a new copy of the array
     * in order to get the right orientation and
     * because we can't just re-use the buffer with the
     * data in the order it is in.
     */
    Py_INCREF(self);
    if (((order == NPY_CORDER && !PyArray_IS_C_CONTIGUOUS(self)) ||
         (order == NPY_FORTRANORDER && !PyArray_IS_F_CONTIGUOUS(self)))) {
        int success = 0;
        success = _attempt_nocopy_reshape(self, ndim, dimensions,
                                          newstrides, order);
        if (success) {
            /* no need to copy the array after all */
            strides = newstrides;
        }