title: Remove numbers from a string with a letter in front
body: <pre><code>combined['Cabin'] = combined['Cabin'].map(lambda c : c[0])
  </code></pre>
  
  <p>I'm following a tutorial, except this line throws the error <code>TypeError: 'float' object has no attribute '__getitem__'</code></p>
  
  <p>Anyway to fix this? </p>
  
  <p>My column's data looks like
  <a href="http://i.stack.imgur.com/dYHmw.png" rel="nofollow">Column</a></p>
  
  <p>Thanks!</p>
  
  <pre><code>def process_cabin():
  
  global combined
  
  # replacing missing cabins with U (for Unknown)
  combined.Cabin.fillna('U',inplace=True)
  
  # mapping each Cabin value with the cabin letter
  combined['Cabin'] = combined['Cabin'].map(lambda c : c[0])
  
  # dummy encoding ...
  cabin_dummies = pd.get_dummies(combined['Cabin'],prefix='Cabin')
  
  combined = pd.concat([combined,cabin_dummies],axis=1)
  
  combined.drop('Cabin',axis=1,inplace=True)
  
  status('cabin')
  </code></pre>
  
  <p>`</p>
  
  <pre><code>---------------------------------------------------------------------------
  TypeError                                 Traceback (most recent call last)
  &lt;ipython-input-152-70714b711c6d&gt; in &lt;module&gt;()
  ----&gt; 1 process_cabin()
  
  &lt;ipython-input-151-d9bb11cabd2c&gt; in process_cabin()
        7 
        8     # mapping each Cabin value with the cabin letter
  ----&gt; 9     combined['Cabin'] = combined['Cabin'].map(lambda c : c[0])
       10 
       11 
  
  C:\Users\Data.Steve-PC\Python\Anaconda\lib\site-packages\pandas\core\series.pyc in map(self, arg, na_action)
     2014                                      index=self.index).__finalize__(self)
     2015         else:
  -&gt; 2016             mapped = map_f(values, arg)
     2017             return self._constructor(mapped,
     2018                                      index=self.index).__finalize__(self)
  
  pandas\src\inference.pyx in pandas.lib.map_infer (pandas\lib.c:58435)()
  
  &lt;ipython-input-151-d9bb11cabd2c&gt; in &lt;lambda&gt;(c)
        7 
        8     # mapping each Cabin value with the cabin letter
  ----&gt; 9     combined['Cabin'] = combined['Cabin'].map(lambda c : c[0])
       10 
       11 
  
  TypeError: 'float' object has no attribute '__getitem__'
  </code></pre>