message: plot_diagram when there are no finite points
diff: @@ -327,9 +327,20 @@ class Tomato:
  """
  import matplotlib.pyplot as plt
  + if self.diagram_.size > 0:
  plt.plot(self.diagram_[:, 0], self.diagram_[:, 1], "ro")
  l = self.diagram_[:, 1].min()
  r = max(self.diagram_[:, 0].max(), self.max_density_per_cc_.max())
  + else:
  + l = self.max_density_per_cc_.min()
  + r = self.max_density_per_cc_.max()
  + if l == r:
  + if l > 0:
  + l, r = .9 * l, 1.1 * r
  + elif l < 0:
  + l, r = 1.1 * l, .9 * r
  + else:
  + l, r = -1., 1.
  plt.plot([l, r], [l, r])
  plt.plot(
  self.max_density_per_cc_, numpy.full(self.max_density_per_cc_.shape, 1.1 * l - 0.1 * r), "ro", color="green"
  