title: write list of xts objects to excel
body: <p>I have a list of 337 XTS objects which looks like this: </p>
  
  <pre><code>&gt; head(blowup.instances)
  $`AERI.US.Equity`
             AERI.US.Equity
  2015-04-24     -0.6363379
  
  $SRPT.US.Equity
             SRPT.US.Equity
  2013-11-12     -0.6400985
  2016-01-15     -0.5485299
  
  $PTCT.US.Equity
             PTCT.US.Equity
  2016-02-23      -0.616419
  </code></pre>
  
  <p>When I try to write them to a csv, it does not work:</p>
  
  <pre><code>&gt; write.csv(blowup.instances, "blowupInstances.csv")
  Error in (function (..., row.names = NULL, check.rows = FALSE, check.names = TRUE,  : 
    arguments imply differing number of rows: 1, 2, 3, 7, 4, 9, 5, 6, 18, 37, 8, 10, 78, 25, 11, 12, 20, 59, 17, 19, 27, 29, 16, 14, 31, 15, 51, 28, 54
  </code></pre>
  
  <p>Now I know why this doesn't work, but I want to know a solution to this other than writing out a large data frame full of <code>NA</code> values that I would have to remove in Excel. Any ideas?</p>