title: Extend a weekly times series into daily
body: <p>I have an xts time series of weekly values</p>
  
  <pre><code>Jan 4 2004, 0.99
  Jan 11 2004, 1.11
  Jan 18 2004, 1.06
  ....
  </code></pre>
  
  <p>and I want to covert it to daily values</p>
  
  <pre><code>Jan 4 2004, 0.99
  Jan 5 2004, 0.99
  Jan 6 2004, 0.99
  ....
  Jan 10 2004, 0.99
  Jan 11 2004, 1.11
  Jan 12 2004, 1.11
  Jan 13 2004, 1.11
  ....
  </code></pre>
  
  <p>where each value is replicated for the following 6 days.</p>
  
  <p>How can I do this in R?</p>