title: SAS: Using Do/Loop in a Proc Transpose
body: <p>I'm  not very familiar with Do Loops in SAS and was hoping to get some help.  I have data that looks like this:</p>
  
  <p>Product A: 1
  <p>
  Product A: 2
  <p>
  Product A: 4</p>
  
  <p>I'd like to transpose (easy) and flag that Product A: 3 is missing, but I need to do this iteratively to the i-th degree since the number of products is large.</p>
  
  <p>If I run the transpose part in SAS, my first column will be 1, second column will be 2, and third column will be 4 - but I'd really like the third column to be missing and the fourth column to be 4.</p>
  
  <p>Any thoughts?  Thanks.</p>