title: String manipulation in list of lists in Python
body: <p>I have a list containing hundreds of sub lists. The list is from a database table and the sub lists are the rows of that table, so the sub lists all have the same number of entries, and the entries are in the same format as in the corresponding sub lists. Here is an example:</p>
  
  <pre><code>persons = [['2014-2-20', 'Ivan', 'Jones', 'Moscow', '21-0049', 'Green'], ['2014-1-12', 'Mike', 'Dyson', 'Glasgow', '9/30-6', 'Green']] ...etc
  </code></pre>
  
  <p>How can I edit all the 5th fields to remove any '-'and '/' signs?</p>
  
  <p>After removing the unwanted signs, how could I make a new list containing all the info on the persons where 1) the 5th field 2nd last figure is a 4, and 2) the 6th field color is 'Blue'?</p>