old_contents: #!/usr/bin/env python3
  from plotly import tools as toolsly
  from plotly.offline import plot, init_notebook_mode
  import plotly.graph_objs as go
  import numpy as np
  
  ##### parameters for everything
  
  alpha = 10 # prey growth
  beta  = 1 # predator eat
  delta = 10. # predator growth
  gamma = 1 # predator death
  
  # second fixed point
  (xfixed, yfixed) = (gamma /delta, alpha / beta)
  
  # plotting parameters
  xmax = 2. * xfixed
  ymax = 2. * yfixed
  numarrows = 20.
  
  # grid for everything
  x,y = np.meshgrid(np.arange(0, xmax, xmax/numarrows), np.arange(0, ymax, ymax/numarrows))
  
  # vector of arrows
  u = alpha * x - beta * x * y
  v = delta * x * y - gamma * y
  
  ####################
  
  title = 'alpha=%.1f beta=%.1f delta=%.1f gamma=%.1f' % (alpha, beta, delta, gamma)
  ext = '_'.join([str(item) for item in [alpha, beta, delta, gamma]])
  filename='quiverplot_'+ext+'.html'
  
  htmlline = '</td><td>'.join([str(item) for item in [alpha, beta, delta, gamma]])
  htmlline = '<tr><td>' + htmlline + '</td><a href=\'' + filename + '\'>link</a></td></tr>'
  print(htmlline)
  
  # fixed points
  points = go.Scatter(x=[0, xfixed], y=[0, yfixed],
                      mode='markers',
                      marker=dict(size=12),
                      name='fixed points',)
  
  options = {}
  if len(ext) <= 0:
      options['visible'] = 'legendonly'
  
  fig = toolsly.FigureFactory.create_quiver(x, y, u, v,
                                            scale=.01, arrow_scale=.1,
                                            name='density', **options)
  
  fig['data'].append(points)
  fig['layout']['xaxis'] = dict(range=[0., xmax])
  fig['layout']['yaxis'] = dict(range=[0., ymax])
  fig['layout']['title'] = title
  plot(fig, show_link=False, filename='lotka_volterra/'+ filename)
  
  
  # http://tributary.io/inlet/5211034
  # http://tributary.io/inlet/5211034
  
new_contents: #!/usr/bin/env python3
  from plotly import tools as toolsly
  from plotly.offline import plot
  import plotly.graph_objs as go
  import numpy as np
  
  ##### parameters for everything
  
  alpha = 10 # prey growth
  beta  = 1 # predator eat
  delta = 10. # predator growth
  gamma = 1 # predator death
  
  # second fixed point
  (xfixed, yfixed) = (gamma /delta, alpha / beta)
  
  # plotting parameters
  xmax = 2. * xfixed
  ymax = 2. * yfixed
  numarrows = 20.
  
  # grid for everything
  x,y = np.meshgrid(np.arange(0, xmax, xmax/numarrows), np.arange(0, ymax, ymax/numarrows))
  
  # vector of arrows
  u = alpha * x - beta * x * y
  v = delta * x * y - gamma * y
  
  ####################
  
  title = 'alpha=%.1f beta=%.1f delta=%.1f gamma=%.1f' % (alpha, beta, delta, gamma)
  ext = '_'.join([str(item) for item in [alpha, beta, delta, gamma]])
  filename='quiverplot_'+ext+'.html'
  
  htmlline = '</td><td>'.join([str(item) for item in [alpha, beta, delta, gamma]])
  htmlline = '<tr><td>' + htmlline + '</td><a href=\'' + filename + '\'>link</a></td></tr>'
  print(htmlline)
  
  # fixed points
  points = go.Scatter(x=[0, xfixed], y=[0, yfixed],
                      mode='markers',
                      marker=dict(size=12),
                      name='fixed points',)
  
  options = {}
  if len(ext) <= 0:
      options['visible'] = 'legendonly'
  
  
  fig = toolsly.FigureFactory.create_quiver(x, y, u, v,
                                            scale=.01, arrow_scale=.1,
                                            name='density', **options)
  
  fig['data'].append(points)
  fig['layout']['xaxis'] = dict(range=[0., xmax])
  fig['layout']['yaxis'] = dict(range=[0., ymax])
  fig['layout']['title'] = title
  plot(fig, show_link=False, filename='lotka_volterra/'+ filename)
  
  # http://tributary.io/inlet/5211034
  
subject: Remove unused content