title: wrong x axis label for time series plot of daily data
body: <p>I have 4 years of historical daily data. I plotted time series with command <code>plot()</code> and put <code>xaxt="n"</code> to customize the x axis. If i want to put daily ticks in the plot and labels for each day, my plot becomes too messy so I wanted to only show ticks for month-years. For example if I have 3 years of data, I only want to put 36 ticks in the x axis each showing the corresponding year and month. I spent a day reading a lot of questions in how to customize x axis but none of the methods worked for my case. I really dont know what else I can do. Here is the code I used: </p>
  
  <pre><code>plot(x,xaxt="n")
  ticks &lt;- seq.Date(as.Date("2007-01-01"),as.Date("2009-12-31"),"months")
  labels &lt;- seq(as.Date("2007-01-01"),as.Date("2009-12-31"),"months")
  axis(1,ticks,labels,format="%b%Y")
  </code></pre>
  
  <p>I first used the following code for ticks:</p>
  
  <pre><code>ticks&lt;- seq(as.Date("2007-01-01"),as.Date("2009-12-31"),"months")
  </code></pre>
  
  <p>it did not work as ticks should be numeric not characters. I saw <a href="http://r.789695.n4.nabble.com/no-x-label-using-axis-Date-td4692034.html" rel="nofollow">here</a> that I can use the first code I used but it did not work for my case. I highly appreciate if anybody can give me some hints on that.  Thanks</p>