title: Filling missing data after outer join
body: <p>I have two time series which are at the same sampling rate.  I would like to perform an outer join and then fill in any missing data (post outer join, there can be points in time where data exists in one series but not the other even though they are the same sampling rate) with the most recent previous value.</p>
  
  <p>How can I perform this operating using Deedle?</p>
  
  <p>Edit:</p>
  
  <p>Based on <a href="http://bluemountaincapital.github.io/Deedle/timeseries.html" rel="nofollow">this</a>, I suppose you can re-sample before the join like so:</p>
  
  <pre><code>// Get the most recent value, sampled at 2 hour intervals
  someSeries|&gt; Series.sampleTimeInto
    (TimeSpan(2, 0, 0)) Direction.Backward Series.lastValue
  </code></pre>
  
  <p>After doing this you can safely Join.  Perhaps there is another way?</p>