title: How to sort Python's PrettyTable integer column correctly
body: <p>We have a problem sorting a <code>Population</code> column. The issue is that 
  PrettyTable reads all data from a CSV file as strings and sorts the integer values as strings. How to fix this?</p>
  
  <pre><code>#!/usr/bin/python3
  
  from prettytable import from_csv
  
  with open("data.csv", "r") as fp: 
  
      x = from_csv(fp)
  
  x.sortby = "Population"
  print(x)
  </code></pre>
  
  <p><code>data.csv</code></p>
  
  <pre><code>"City name", "Area", "Population", "Annual Rainfall"
  "Adelaide", 1295,1158259, 600.5
  "Brisbane", 5905,1857594, 1146.4
  "Darwin", 11200000,120900, 1714.7
  "Hobart", 1357,205556, 619.5
  "Sydney", 2058,4336374, 1214.8
  "Melbourne", 1566,3806092, 646.9
  "Perth", 5386,1554769, 869.4
  </code></pre>