priority_flow.find_orphan
=========================

.. py:module:: priority_flow.find_orphan

.. autoapi-nested-parse::

   Find Orphan functions for PriorityFlow.

   This module provides functions to find orphan branches - unprocessed river cells
   that have D8 neighbors on the river network or on the boundary. This is useful
   for identifying missed cells during river network processing.



Functions
---------

.. autoapisummary::

   priority_flow.find_orphan.find_orphan


Module Contents
---------------

.. py:function:: find_orphan(dem: numpy.ndarray, mask: numpy.ndarray, marked: numpy.ndarray) -> Dict[str, Union[int, numpy.ndarray, None]]

   Find orphan branches in river network processing.

   Function to look for unprocessed river cells that have D8 neighbors on the
   river network or on the boundary.

   :param dem: Digital elevation model matrix
   :type dem: np.ndarray
   :param mask: River network mask (1 for river cells, 0 for non-river cells)
   :type mask: np.ndarray
   :param marked: Matrix of grid cells that have been processed (1 for processed, 0 for unprocessed)
   :type marked: np.ndarray

   :returns: A dictionary containing:
             - 'norphan': Number of orphaned branches found
             - 'queue': Queue of marked neighbors to be processed (numpy array with columns: x, y, elevation)
   :rtype: Dict[str, Union[int, np.ndarray, None]]

   .. rubric:: Notes

   This function implements an orphan detection algorithm that:
   1. Identifies unprocessed river cells (masked but not marked)
   2. Checks D8 connectivity to find marked neighbors
   3. Counts marked neighbors for each orphan cell
   4. Creates a processing queue from marked neighbors of orphan cells

   The algorithm uses D8 connectivity (8-directional) to ensure complete
   neighbor checking and proper orphan identification.