title: pandas DataFrame : extract data in a 2 columns dataframe
body: <p>I have a 2 columns df with a redundant but irregular structure ('name', 'code' and 'w' associated with a'code') I would like to extract.
  Here the DF :</p>
  
  <pre><code>    import pandas as pd
      pd.DataFrame([('name','john'),
                    ('date','NaN'),
                    ('curr','NaN'),
                    ('code','w'),
                    ('123',0.4),
                    ('456',0.5),
                    ('789','0.1'),
                    ('name','Elsa'),
                    ('date','NaN'),
                    ('curr','NaN'),
                    ('code','w'),
                    ('112',0.3),
                    ('243',0.3),
                    ('789','0.3'),
                    ('351','0.1')               
                    ])
  </code></pre>
  
  <p>I would like to extract this :</p>
  
  <pre><code>    name code w
      john 123 0.4
      john 456 0.5
      john 789 0.1
      elsa 112 0.3
      elsa 243 0.3
      elsa 789 0.3
      elsa 351 0.1
  </code></pre>
  
  <p>How can i do this ?
  thank you </p>