title: How to compare dataframes from two different months on a single key
body: <p>Pretty new to Python, but as an SEO I'm looking at the benefits of using notebooks in my workflow.</p>
  
  <p>I've got two excel files which I've cleaned and imported into a new notebook using pandas.</p>
  
  <p>I'm trying to compare position changes and create a new data frame with new columns to show previous, new, and changes in positions.</p>
  
  <p>Have a look at the data below:</p>
  
  <p><img src="https://i.stack.imgur.com/v7gDf.png" alt="Df1"></p>
  
  <p><img src="https://i.stack.imgur.com/fRfDZ.png" alt="Df2"></p>