title: How to multiply one column by another in a csv file and re-write
body: <p>I have some data in csv format and I need to perform a multiplication of the 3rd column by the 6th column and append the results to the end. My data is as follows: </p>
  
  <pre><code> TITLE,TITLE,T,T,T,T
   data,data,5,data,data,98.7,data
   data,data,2,data,data,97,data
   data,data,5,data,data,98,data
   data,data,4,data,data,8.7,data
   data,data,5,data,data,9.7,data
   data,data,12.5,data,data,198.7,data
  </code></pre>
  
  <p>I am really new to coding, but my attempt was as follows:
      import csv
      import datetime
      import copy
      from collections import defaultdict</p>
  
  <pre><code>class_col = 2
  data_col = 5
  
  with open('minitest.csv', 'r') as f:
      data = [line.strip().split(',') for line in f]
  
  for row in data:
      class_col*data_col
  
  with open('minitest_edit.csv', 'w') as nf:
      nf.write('\n'.join(','.join(row) for row in data))
  
  print "done"
  </code></pre>
  
  <p>I didn't get any errors come up, any suggestions? Thanks OS"</p>