title: Convert Column Name from int to string in pandas
body: <p>I have a pandas dataframe with mixed column names:</p>
  
  <p>1,2,3,4,5, 'Class'</p>
  
  <p>When I save this dataframe to h5file, it says that the performance will be affected due to mixed types. How do I convert the integer to string in pandas?</p>