voxel_average_w_uncertainty
==================================================================

.. py:function:: petpal.preproc.regional_tac_extraction.voxel_average_w_uncertainty(pet_voxels: numpy.ndarray) -> tuple[numpy.ndarray, numpy.ndarray]

   Spatially average flattened PET voxels and get the standard deviation as well.

   Takes a 2D M x N numpy array with M voxels and N time frames and returns a tuple of 1D N-length
   numpy arrays with the mean activity and standard deviation for each time frame.

   :param pet_voxels: 2D M x N array of PET voxels with M voxels and N time frames.
                      Typically takes the output of
                      :func:`~petpal.preproc.regional_tac_extraction.apply_mask_4d`.
   :type pet_voxels: np.ndarray

   :returns: *average_w_uncertainty (tuple[np.ndarray, np.ndarray])* --

             Average and standard deviation of
                 PET voxels for each time frame.