title: How to access value_counts() data in pandas?
body: <p>When I do a count of values in a Panda, who do I access a column name?</p>
  
  <p>Consider the US Census dataset. I can count the number of counties in each state with:</p>
  
  <pre><code>df2["STNAME"].value_counts()
  </code></pre>
  
  <p>Which returns a series which looks like this: </p>
  
  <pre><code>Alabama    24
  Alaska     23
  Arizona     1
  etc ...
  Name: STNAME, dtype: int64
  </code></pre>
  
  <p>How do I access the State name (the STNAME, which actually I'm not sure is the index, since in SQL terms this is, I think, just a view on the data). </p>