text: from __future__ import absolute_import
  
  #--------------------------
  def setplot(plotdata=None):
  #--------------------------
      
      """ 
      Specify what is to be plotted at each frame.
      Input:  plotdata, an instance of clawpack.visclaw.data.ClawPlotData.
      Output: a modified version of plotdata.
      
      """ 
  
      if plotdata is None:
          from clawpack.visclaw.data import ClawPlotData
          plotdata = ClawPlotData()
  
      plotdata.clearfigures()
  
      # Figures corresponding to Figure 9.5 of LeVeque, "Finite Volume
      # Methods for Hyperbolic Problems," 2002 (though more of them)
  
      # Tuples of (variable name, variable number)
      figdata = [('Pressure', 0),
                 ('Velocity', 1)]
  
      # Afteraxes function: draw a vertical dashed line at the interface
      # between different media
      def draw_interface(current_data):
          import pylab
          pylab.plot([0., 0.], [-1000., 1000.], 'k--')
  
      for varname, varid in figdata:
          plotfigure = plotdata.new_plotfigure(name=varname, figno=varid)
  
          plotaxes = plotfigure.new_plotaxes()
          plotaxes.xlimits = [-5., 5.]
          plotaxes.ylimits = [-0.5, 1.5]    # Good for both vars because of near-unit impedance
          plotaxes.title = varname
          plotaxes.afteraxes = draw_interface
  
          plotitem = plotaxes.new_plotitem(plot_type='1d_plot')
          plotitem.plot_var = varid
          plotitem.color = 'b'
  
      plotdata.printfigs = True          # Whether to output figures
      plotdata.print_format = 'png'      # What type of output format
      plotdata.print_framenos = 'all'    # Which frames to output
      plotdata.print_fignos = 'all'      # Which figures to print
      plotdata.html = True               # Whether to create HTML files
      plotdata.latex = False             # Whether to make LaTeX output
  
      return plotdata
  
  