title: Want to save multiple plots in PDF document
body: <p>I want to save every plot in a PDF document, but only the last plot is saved. </p>
  
  <p>Here is my code:</p>
  
  <pre><code>for pair in indices:
      y1 = c[pair[0]]
      y2 = c[pair[1]]
  
      fig = plt.figure(figsize=(10,4))
      ax1 = fig.add_subplot(111)
      ax1.plot(x, y1, "-o", color='b')
      plt.ylabel(pair[0])
  
      ax2 = ax1.twinx()
      ax2.plot(x, y2,"-o" ,color='r')
      for tl in ax2.get_yticklabels():
          tl.set_color('r')
  
      plt.title('Reihe')
      plt.ylabel(pair[1])
  
      plt.savefig("title2.pdf", dpi=300)
  </code></pre>