title: Finding most frequent record in a column from CSV file
body: <p>I have a huge CSV where each line has a user ID. I want to find the UserID that turns up most frequently across the whole set.</p>
  
  <p>I've used <code>DictReader</code> from the <code>csv</code> module to read in the csv, as I think this will be most useful to manipulate individual records later. </p>
  
  <p>I can't find a way to search through the various values for the key "UserID" in my created dictionary and find the most frequent value.</p>
  
  <p>Any help would be greatly appreciated!</p>
  
  <p>Here is my code so far:</p>
  
  <pre><code>import csv
  from time import time
  start = time()
  myData=open("myCSV.csv", "rb" )
  csvReader= csv.DictReader(myData)
  
  # declare counters
  volume = 0
  
  #sum all data usage
  for data in csvReader:
      volume += float(data["volume_total"])
  print "Total : %f" %volume
  
  #calculate processing time
  elapsed = time() - start
  print "Processing time: %f seconds" %elapsed
  </code></pre>