average_across_4d_frames
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.. py:function:: petpal.input_function.idif_necktangle.average_across_4d_frames(pet_4d_data: numpy.ndarray, start_frame: int, end_frame: int) -> numpy.ndarray

   Calculates the mean frame across the specified range of frames in the 4-dimensional PET data.

   :param pet_4d_data: 4-dimensional array representing the PET data.
   :type pet_4d_data: np.ndarray
   :param start_frame: The starting frame index for the mean calculation.
   :type start_frame: int
   :param end_frame: The ending frame index for the mean calculation.
   :type end_frame: int

   :returns: *mean_frame (np.ndarray)* -- The mean frame calculated from the specified range of frames.