title: copying character data down rows
body: <p>I have a ridiculous For loop question, and I apologize in advance, but I cannot figure it out.  Here is a table:</p>
  
  <pre><code>     Site     Date Software EPFU LABO
  3  Site 10 20160517     BCID   70  210
  4  Site 10 20160518     BCID   NA   NA
  5          20160519     BCID   NA   NA
  6          20160520     BCID   NA   NA
  7          20160521     BCID   NA   NA
  8          20160522     BCID   NA   NA
  9  Site 11 20160517     BCID    2  139
  10 Site 11 20160518     BCID   NA    9
  11         20160519     BCID   NA   NA
  12         20160520     BCID   NA   NA
  13         20160521     BCID   NA   NA
  14         20160522     BCID   NA   NA`
  </code></pre>
  
  <p>How do I fill the gaps below "Site 10" with text that says "Site 10" until it reaches "Site 11", at which point the cycle repeats with the text "Site 11" and so on...Any help would be appreciated.  Site is currently a character class, but I can make it a factor if that will simplify this mess.  One additional problem is that the "blank" cells are actually a range of "","       ", and "*"anything that will simplify this mess.</p>