title: SAS - Fill values for each group
body: <p>I have a data set that looks like this:</p>
  
  <pre><code>Stop    Group
  JFK     A
  JFK     B
  JFK     C
  AMS     A
  AMS     B
  AMS     C
  LHR     A
  SFO     B
  </code></pre>
  
  <p>I'm trying to generate a new data set where each <code>Stop</code> will have values A, B and C. For example, JFK and AMS already have A-C, so no change is needed. LHR needs B and C added and SFO needs A and C added. The output dataset should look like this:</p>
  
  <pre><code>JFK A
  JFK B
  JKF C
  AMS A
  AMS B
  AMS C
  LHR A
  LHR B
  LHR C
  SFO A
  SFO B
  SFO C
  </code></pre>
  
  <p>Any ideas? Thanks!</p>