title: Problems regarding csv.DictReader
body: <pre><code>list3 = []
  
  with open('**directory**') as csvfile:
      reader = csv.DictReader(csvfile)
      for row in reader:
          list3.append(row)
  </code></pre>
  
  <p>I'm completely new to data analysis using Python, and require some assistance. </p>
  
  <p>The file I'm accessing contains data from 5 people (CSV file). There are 3 columns - participant number, pre-task Score, and post-task Score. </p>
  
  <p>I'm essentially trying to access this file (using csv.DictReader) and manipulate the data. By this, I mean I want to calculate the difference between the post-task score and pre-task score, for each participant, and print this to the screen. </p>
  
  <p>However, I'm not sure how to do this. I can print each row to the screen, and I can save each row in a list (as I've done above) - but I'm clueless as to how I am to manipulate/deal with this data. I'm wondering if there is something better than the module I'm currently using.</p>