title: List of lists conversion to pandas DataFrame
body: <p>I have a list of lists that looks like this:</p>
  
  <pre><code>[[('category', 'evaluation'), ('polarity', 'pos'), ('strength', '1'), ('type', 'good')],
  [('category', 'intensifier'), ('type', 'shifter')],
  [('category', 'evaluation'), ('polarity', 'pos'), ('strength', '2'), ('type', 'good')],
  </code></pre>
  
  <p>Note that not all lists contain all the attributes. </p>
  
  <p>I would like, if possible, to convert this to a DataFrame, where each list represents a new row and the names of the columns would be given by the first element (e.g. <em>'category'</em>, <em>'polarity'</em>, <em>'strength'</em>, <em>'type'</em>). In the end, the DataFrame should look like this:</p>
  
  <pre><code>           category     polarity     strength     type
  df[0]:    evaluation      pos           1         good
  df[1]:    intensifier     NaN          NaN       shifter
  df[2]:    evaluation      pos           2         good
  </code></pre>
  
  <p>Any help would be greatly appreciated. </p>