title: groupby and join text column
body: <p>I have a csv file with this header <code>text|business_id</code></p>
  
  <p>I wanna group all texts related to one business </p>
  
  <p>I used <code>review_data=review_data.groupby(['business_id'])['text'].apply("".join)</code></p>
  
  <p>The <code>review_data</code> is like:</p>
  
  <pre><code>                                                   text  \
  0     mr hoagi institut walk doe seem like throwback...   
  1     excel food superb custom servic miss mario mac...   
  2     yes place littl date open weekend staff alway ... 
  
           business_id  
  0     5UmKMjUEUNdYWqANhGckJw  
  1     5UmKMjUEUNdYWqANhGckJw  
  2     5UmKMjUEUNdYWqANhGckJw
  </code></pre>
  
  <p>I get this error: <code>TypeError: sequence item 131: expected string, float found
  </code> </p>
  
  <p>these are the lines 130 to 132: </p>
  
  <pre><code>130 use order fair often  past 2 year food get progress wors everi time order  doesnt help owner alway regist rude everi time  final decid im done  dont think feel let inconveni order food restaur  let alon one food isnt even good also insid dirti heck  deliv food bmw cant buy scrub brush  found golden dragon collier squar 100 time better|SQ0j7bgSTazkVQlF5AnqyQ
  131 popular denni|wqu7ILomIOPSduRwoWp4AQ
  132 want smth quick late night would say denni|wqu7ILomIOPSduRwoWp4AQ
  </code></pre>