title: Dask reading CSV, setting partition as CSV length
body: <p>I'm trying to write code that will read from a set of CSVs named <code>my_file_*.csv</code> into a Dask dataframe. </p>
  
  <p>Then I want to set the partitions based on the length of the CSV. I'm trying to map a function on each partition and in order to do that, each partition must be the whole CSV.</p>
  
  <p>I've tried to reset the index, and then set partitions based on the length of each CSV but it looks like the index of the Dask dataframe is not unique. </p>
  
  <p>Is there a better way to partition based on the length of each CSV?</p>