d><p>A SpatialPolygonsDataFrame or SpatialPointsDataFrame
representing the original centroids or boundaries of the travel flow data.
Note that in the case of a SpatialPointsDataFrame, the entirety of the flow
will be allocated to the polygon in which the point is located rather than
being distributed by area.</p></td>
    </tr>
    <tr>
      <th>aggzones</th>
      <td><p>A SpatialPolygonsDataFrame containing the new
boundaries to aggregate to.</p></td>
    </tr>
    <tr>
      <th>aggzone_points</th>
    