title: R convert factor to date with month as characters
body: <p>I'm trying to convert a factor to date but I keep getting NA values. The format of the date value I have as date is like: dd-mmm-yy. For example with the following code:</p>
  
  <pre><code>dates &lt;- c('21-Feb-16', '22-Feb-16', '23-Feb-16')
  valx &lt;- c(100,200,300)
  df.dates &lt;- data.frame(dates, valx)
  </code></pre>
  
  <p>I have tried some of the examples in <a href="https://stackoverflow.com/questions/4843969/plotting-time-series-with-date-labels-on-x-axis">here</a>, but when I try to convert the date I get an NA value</p>
  
  <pre><code>as.Date(df.dates$dates, format = "%d/%m/%Y")
  [1] NA NA NA
  </code></pre>
  
  <p>My intention is to do a time line chart, but I cannot figure out how to convert the date properly</p>