quickpaver.span_to_node_numbers_2d#

quickpaver.span_to_node_numbers_2d(span: ndarray[tuple[Any, ...], dtype[int64]] | Tuple[slice, slice] | slice, nx: int, ny: int) → ndarray[tuple[Any, ...], dtype[int64]][source]#

Convert a 2D grid span to flattened node numbers.

The input span is applied to a temporary boolean-like array with shape (nx, ny). All selected cells are converted from 2D grid indices (ix, iy) to flattened regular-grid node numbers using rlg_idx_to_nn().

Parameters:

  • span (Union[NDArrayInt, Tuple[slice, slice], slice]) – NumPy-style selection applied to a 2D array of shape (nx, ny). Examples include slice(None), (slice(0, 2), slice(None)), or an integer index array compatible with NumPy indexing.

  • nx (int) – Number of grid cells along the x-axis.

  • ny (int) – Number of grid cells along the y-axis.

Returns:

One-dimensional array of flattened node numbers corresponding to the selected cells. The returned array has dtype np.int32.

Return type:

NDArrayInt

Notes

The grid follows the internal (x, y) array convention, meaning that the temporary selection array has shape (nx, ny) rather than the image-style convention (ny, nx).

The flattened numbering convention is:

node_number = ix + iy * nx

This function operates on grid cells, not on grid vertices.