title: insert new rows to the time series data, with date added automatically
body: <p>I have a time-series data frame looks like:</p>
  
  <pre><code>            TS.1
  2015-09-01 361656.7
  2015-09-02 370086.4
  2015-09-03 346571.2
  2015-09-04 316616.9
  2015-09-05 342271.8
  2015-09-06 361548.2
  2015-09-07 342609.2
  2015-09-08 281868.8
  2015-09-09 297011.1
  2015-09-10 295160.5
  2015-09-11 287926.9
  2015-09-12 323365.8
  </code></pre>
  
  <p>Now, what I want to do is add some new data points (rows) to the existing data frame, say,</p>
  
  <pre><code>320123.5
  323521.7
  </code></pre>
  
  <p>How can I added corresponding date to each row? The data is just sequentially inhered from the last row.</p>
  
  <p>Is there any package can do this automatically, so that the only thing I do is to insert new data point?</p>