title: Finding median of entire pandas Data frame
body: <p>I'm trying to find the median flow of the entire dataframe. The first part of this is to select only certain items in the dataframe.</p>
  
  <p>There were two problems with this, it included parts of the data frame that aren't in 'states'. Also, the median was not a single value, it was based on row. How would I get the overall median of all the data in the dataframe? </p>