class_docstr: A file handler class for VIIRS compact format.
class_docstr_tok: ["A","file","handler","class","for","VIIRS","compact","format","."]
docstr: Compute the expansion coefficients.
docstr_tok: ["Compute","the","expansion","coefficients","."]
code: def expansion_coefs(self):
      """Compute the expansion coefficients."""
      if self._expansion_coefs is not None:
          return self._expansion_coefs
      v_track = (
          np.arange(self.scans * self.scan_size) % self.scan_size
          + self.track_offset
      ) / self.scan_size
      self.tpz_sizes = self.tpz_sizes.persist()
      self.nb_tiepoint_zones = self.nb_tiepoint_zones.persist()
      col_chunks = (self.tpz_sizes * self.nb_tiepoint_zones).compute()
      self._expansion_coefs = da.map_blocks(
          get_coefs,
          self.c_align,
          self.c_exp,
          self.tpz_sizes,
          self.nb_tiepoint_zones,
          v_track=v_track,
          scans=self.scans,
          scan_size=self.scan_size,
          scan_offset=self.scan_offset,
          dtype=np.float64,
          new_axis=[0, 2],
          chunks=(self.scans * self.scan_size, tuple(col_chunks), 4),
      )
  
      return self._expansion_coefs
  
imports: import logging
  from contextlib import suppress
  from datetime import datetime, timedelta
  import dask.array
  import h5py
  import numpy
  import xarray
  from satpy.readers.file_handlers import BaseFileHandler
  from satpy.readers.utils import np2str
  from satpy.utils import angle2xyz, get_legacy_chunk_size, lonlat2xyz, xyz2angle, xyz2lonlat
label_desc: Use image node_id 10 for calling the VIIRSCompactFileHandler obj's underlying member method code with example usage: obj.expansion_coefs() and returns: self, self