title: Converting year and month ("yyyy-mm" format) to a date?
body: <p>I have a dataset that looks like this:</p>
  <pre><code>Month    count
  2009-01  12
  2009-02  310
  2009-03  2379
  2009-04  234
  2009-05  14
  2009-08  1
  2009-09  34
  2009-10  2386
  </code></pre>
  <p>I want to plot the data (months as x values and counts as y values). Since there are gaps in the data, I want to convert the Information for the Month into a date. I tried:</p>
  <pre><code>as.Date(&quot;2009-03&quot;, &quot;%Y-%m&quot;)
  </code></pre>
  <p>But it did not work. Whats wrong? It seems that <code>as.Date()</code> requires also a day and is not able to set a standard value for the day? Which function solves my problem?</p>