title: Avoid coinciding lines and markers in pyplot
body: <p>I have two problems which are based on a similar fact. If I use Matplotlib to plot lines which happen to lie on one another partly in that specific area only one of them is shown.</p>
  
  <p>Example one</p>
  
  <pre><code>import matplotlib.pyplot as plt
  plt.plot([1,2],[1,1],'r-')
  plt.plot([1.5,3],[1,1],'b-')
  plt.show()
  </code></pre>
  
  <p>Example two</p>
  
  <pre><code>import matplotlib.pyplot as plt
  plt.plot([0.5,3],[0,0],'b-',marker='o')
  ax = gca()
  ax.set_xlim(0.4)
  ax.spines['bottom'].set_position(('data',0))
  ax.spines['left'].set_position(('data',0))
  plt.show()
  </code></pre>
  
  <p>I would like to have Matplotlib to plot them 1 px apart, so that one could see both lines, if that is anyhow possible.</p>
  
  <p>The second thing is the same for markers. I would like matplotlib to set to markers, which have to be drawn to the same spot in the euclidean space to be drawn blow each other, because else they are barely visible.</p>
  
  <p>Thanks in Advance </p>