title: Convert date to day-of-week in R
body: <p>I have a date in this format in my data frame: </p>
  
  <pre><code>"02-July-2015"
  </code></pre>
  
  <p>And I need to convert it to the day of the week (i.e. 183). Something like: </p>
  
  <pre><code>df$day_of_week &lt;- weekdays(as.Date(df$date_column))
  </code></pre>
  
  <p>But this doesn't understand the format of the dates. </p>