title: Scatter plot with a huge amount of data
body: <p>I would like to use <a href="http://en.wikipedia.org/wiki/Matplotlib" rel="noreferrer">Matplotlib</a> to generate a scatter plot with a huge amount of data (about 3 million points). Actually I've 3 vectors with the same dimension and I use to plot in the following way.</p>
  
  <pre><code>import matplotlib.pyplot as plt
  import numpy as np
  from numpy import *
  from matplotlib import rc
  import pylab
  from pylab import * 
  fig = plt.figure()
  fig.subplots_adjust(bottom=0.2)
  ax = fig.add_subplot(111)
  plt.scatter(delta,vf,c=dS,alpha=0.7,cmap=cm.Paired)
  </code></pre>
  
  <p>Nothing special actually. But it takes too long to generate it actually (I'm working on my MacBook Pro 4 GB RAM with Python 2.7 and Matplotlib 1.0). Is there any way to improve the speed?</p>