title: Pandas DataFrame chunks: writing a DataFrame generator object to_csv
body: <p>I'm reading a large amount of data from a database via pd.read_sql(...chunksize=10000) which generates a df generator object.</p>
  
  <p>While I can still work with that dataframe in merging it with pd.merge(df,df2...) some functions are no longer available, such as df.to_cs(...)</p>
  
  <p>What is the best way to handle that? How can I write such a dataframe to a CSV? Do I need to iterate over it manually?</p>