title: show month and date in two digits using R
body: <p>I have a column in numeric format as below.</p>
  
  <pre><code>col1:
  9302014  (September 30, 2014)
  10312014 (October 31, 2014)
  1212014  (December 01, 2014)
  1212014  (January 21, 2014)
  </code></pre>
  
  <p>I need to convert the month and date column in col1 to two digits. How can I achieve this in R.</p>
  
  <pre><code>Output:
  09302014
  10312014
  12012014
  </code></pre>