title: Working with data from CSV with Python without using Pandas
body: <p>I am very new to using python to process data on CSV files. I have a CSV file with the data below. I want to take the <strong>averages of the time stamps</strong> for each Sprint, Jog, and Walk column <strong>by session</strong>. The below example has the subject <strong>John Doe</strong> and <strong>Session2</strong> and <strong>Session3</strong> that I would like to find the averages of separately and write them to a new CSV file. Is there a way not using PANDAS but other modules like CSV or Numpy to gather the data by the person (subject) and then by <strong>session</strong>. I have tried to make a dictionary but the keys get overwritten. I have also tried using a List but I cannot figure out how to target the sessions to average them out. Not sure what I am doing wrong. I also tried using dictReader to read the fieldnames and then to process the data but I cannot figure out how to group all the John Doe Session2 data to find the average of the times.</p>
  <pre><code>Subject, Session, Course, Size, Category, Sprint, Jog, Walk
  John Doe, Session2, 17, 2, Bad, 25s, 36s, 55s
  John Doe, Session2, 3, 2, Good, 26s, 35s, 45s
  John Doe, Session2, 1, 2, Good, 22s, 31s, 47s
  John Doe, Session3, 5, 2, Good, 16s, 32s, 55s
  John Doe, Session3, 2, 2, Good, 13s, 24s, 52s
  John Doe, Session3, 16, 2, Bad, 15s, 26s, 49s
  </code></pre>
  <p>PS I say no PANDAS because my groupmates are not adding this module since we have so many other dependencies.</p>