title: sorting an array in python jupyter notebook
body: <p>When I try to sort an array in jupyter notebook using the following syntax, it sorts all rows rather than a single row, throwing the indexes are off.</p>
  
  <p>ADELAIDE = df.groupby('Year')['Passengers_Total'].sum()</p>
  
  <p>What syntax should I use to only sort the 'Passengers_Total' column?</p>