parcellate_right_left
=======================================================

.. py:function:: petpal.preproc.segmentation_tools.parcellate_right_left(segmentation_numpy: numpy.ndarray, region: int, new_right_region: int, new_left_region: int) -> numpy.ndarray

   Divide a region within a segmentation image into right and left values.
   Assumes left and right sides are neatly subdivided by the image midplane,
   with right values below the mean value of the x-axis (zeroth axis) and left
   values above the mean value of the x-axis (zeroth axis).

   Intended to work with FreeSurfer segmentations on images loaded with
   nibabel. Use outside of these assumptions at your own risk.

   :param segmentation_numpy: Segmentation image array loaded with Nibabel, RAS+
                              orientation
   :type segmentation_numpy: np.ndarray
   :param region: Region index in segmentation image to be split into left and right.
   :type region: int
   :param new_right_region: Region on the right side assigned to previous region.
   :type new_right_region: int
   :param new_left_region: Region on the left side assined to previous region.
   :type new_left_region: int

   :returns: *split_segmentation (np.ndarray)* --

             Original segmentation image array with new left and right
                 values.