title: seaborn heatmap using pandas dataframe
body: <p>I am struggling to massage a dataframe in pandas into the correct format for seaborn's heatmap (or matplotlib really) to make a heatmap.</p>
  
  <p>My current dataframe (called data_yule) is:</p>
  
  <pre><code>     Unnamed: 0  SymmetricDivision         test  MutProb      value
  3             3                1.0  sackin_yule    0.100  -4.180864
  8             8                1.0  sackin_yule    0.050  -9.175349
  13           13                1.0  sackin_yule    0.010 -11.408114
  18           18                1.0  sackin_yule    0.005 -10.502450
  23           23                1.0  sackin_yule    0.001  -8.027475
  28           28                0.8  sackin_yule    0.100  -0.722602
  33           33                0.8  sackin_yule    0.050  -6.996394
  38           38                0.8  sackin_yule    0.010 -10.536340
  43           43                0.8  sackin_yule    0.005  -9.544065
  48           48                0.8  sackin_yule    0.001  -7.196407
  53           53                0.6  sackin_yule    0.100  -0.392256
  58           58                0.6  sackin_yule    0.050  -6.621639
  63           63                0.6  sackin_yule    0.010  -9.551801
  68           68                0.6  sackin_yule    0.005  -9.292469
  73           73                0.6  sackin_yule    0.001  -6.760559
  78           78                0.4  sackin_yule    0.100  -0.652147
  83           83                0.4  sackin_yule    0.050  -6.885229
  88           88                0.4  sackin_yule    0.010  -9.455776
  93           93                0.4  sackin_yule    0.005  -8.936463
  98           98                0.4  sackin_yule    0.001  -6.473629
  103         103                0.2  sackin_yule    0.100  -0.964818
  108         108                0.2  sackin_yule    0.050  -6.051482
  113         113                0.2  sackin_yule    0.010  -9.784686
  118         118                0.2  sackin_yule    0.005  -8.571063
  123         123                0.2  sackin_yule    0.001  -6.146121
  </code></pre>
  
  <p>and my attempts using matplotlib was:</p>
  
  <pre><code>plt.pcolor(data_yule.SymmetricDivision, data_yule.MutProb, data_yule.value)
  </code></pre>
  
  <p>which threw the error: </p>
  
  <pre><code>ValueError: not enough values to unpack (expected 2, got 1)
  </code></pre>
  
  <p>and the seaborn attempt was:</p>
  
  <pre><code>sns.heatmap(data_yule.SymmetricDivision, data_yule.MutProb, data_yule.value)
  </code></pre>
  
  <p>which threw:</p>
  
  <pre><code>ValueError: The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().
  </code></pre>
  
  <p>It seems trivial as both functions want rectangular dataset, but I'm missing something, clearly. </p>