title: How can I retrieve the last non-zero value in a column
body: <p>So this is what I see </p>
  
  <pre><code>Column 1 Column 2 Column 3
  
  103.46  15-10-02    150.60
  381.67  15-10-02    150.60
  741.31  15-10-03    0
  14.21   15-10-03    0
  35.37   15-10-05    0
  11.24   15-10-12    19.23
  13.77   15-10-13    0
  </code></pre>
  
  <p>and I'd like to insert the previous non-zero value from column 3 wherever there is a zero in column 3</p>
  
  <p>so I would see something like </p>
  
  <pre><code>Column 1 Column 2 Column 3
  
  103.46  15-10-02    150.60
  381.67  15-10-02    150.60
  741.31  15-10-03    150.60
  14.21   15-10-03    150.60
  35.37   15-10-05    150.60
  11.24   15-10-12    19.23
  13.77   15-10-13    19.23
  </code></pre>
  
  <p>Any help would be greatly appreciated!</p>