title: Plotting heatmap for 3 columns in python with seaborn
body: <pre><code>v1      v2      yy
  15.25   44.34   100.00
  83.05   59.78   100.00
  96.61   65.09   100.00
  100.00  75.47   100.00
  100.00  50.00   100.00
  100.00  68.87   100.00
  100.00  79.35   100.00
  100.00  100.00  100.00
  100.00  63.21   100.00
  100.00  100.00  100.00
  100.00  68.87   100.00
  0.00    56.52   92.86
  10.17   52.83   92.86
  23.73   46.23   92.86
  </code></pre>
  
  <p>In the dataframe above, I want to plot a heatmap using v1 and v2 as x and y axis and yy as the value. How can I do that in python? I tried seaborn:</p>
  
  <pre><code>df = df.pivot('v1', 'v2', 'yy')
  ax = sns.heatmap(df)
  </code></pre>
  
  <p>However, this does not work. Any other solution?</p>