def SetSpan(self, first_arr, last_arr, mint=5 ,maxt=30):
    s_hour = (first_arr / 3600) - 1
    e_hour = (last_arr / 3600) + 1
    self._offset = max(min(s_hour, 23), 0)
    self._tspan = max(min(e_hour - s_hour, maxt), mint)
    self._gwidth = self._tspan * self._hour_grid
dataset/ETHPy150Open google/transitfeed/gtfsscheduleviewer/marey_graph.py/MareyGraph.SetSpan/original