title: Pandas get the age from a date (example: date of birth)
body: <p>How can I calculate the age of a person (based off the dob column) and add a column to the dataframe with the new value?</p>
  
  <p>dataframe looks like the following:</p>
  
  <pre><code>    lname      fname     dob
  0    DOE       LAURIE    03011979
  1    BOURNE    JASON     06111978
  2    GRINCH    XMAS      12131988
  3    DOE       JOHN      11121986
  </code></pre>
  
  <p>I tried doing the following:</p>
  
  <pre><code>now = datetime.now()
  df1['age'] = now - df1['dob']
  </code></pre>
  
  <p>But, received the following error:</p>
  
  <p>TypeError: unsupported operand type(s) for -: 'datetime.datetime' and 'str'</p>