title: Plotting chart with epoch time x axis using matplotlib
body: <p>I have the following code to plot a chart with matplotlib</p>
  
  <pre><code>#!/usr/bin/env python
  import matplotlib.pyplot as plt
  import urllib2
  import json
  
  req = urllib2.urlopen("http://localhost:17668/retrieval/data/getData.json?        pv=LNLS:ANEL:corrente&amp;donotchunk")
  data = json.load(req)
  secs = [x['secs'] for x in data[0]['data']]
  vals = [x['val'] for x in data[0]['data']]
  
  plt.plot(secs, vals)
  plt.show()
  </code></pre>
  
  <p>The secs arrays is epoch time.</p>
  
  <p>What I want is to plot the data in the x axis (secs) as a date (DD-MM-YYYY HH:MM:SS). </p>
  
  <p>How can I do that?</p>