title: Plotting large datasets with pandas
body: <p>I convert an oscilloscope dataset with millions of values into a pandas DataFrame. Next step is to plot it. But Matplotlib needs on my fairly powerful machine ~50 seconds to plot the DataFrame. </p>
  
  <pre><code>import pandas as pd
  import matplotlib.pyplot as plt
  import readTrc    
  
  datX, datY, m = readTrc.readTrc('C220180104_ch2_UHF00000.trc')
  
  srx, sry = pd.Series(datX), pd.Series(datY)
  df = pd.concat([srx, sry], axis = 1)
  df.set_index(0, inplace = True)
  
  df.plot(grid = 1)
  plt.show()
  </code></pre>
  
  <p>Now I found out that there is a way to make matplotlib faster with large datasets by using 'Agg'.</p>
  
  <pre><code>import matplotlib
  matplotlib.use('Agg')
  import pandas as pd
  import matplotlib.pyplot as plt
  import readTrc
  
  datX, datY, m = readTrc.readTrc('C220180104_ch2_UHF00000.trc')
  
  srx, sry = pd.Series(datX), pd.Series(datY)
  df = pd.concat([srx, sry], axis = 1)
  df.set_index(0, inplace = True)
  
  df.plot(grid = 1)
  plt.show()
  </code></pre>
  
  <p>Unfortunately no plot is shown. The process of processing the plot takes ~5 seconds (a big improvement) but no plot is shown. Is this method not compatible with pandas?</p>