title: Convert Factor to Date/Time in R
body: <p>This is the information contained within my dataframe:</p>
  
  <pre><code>## minuteofday: factor w/ 89501 levels "2013-06-01 08:07:00",...
  ## dDdt: num 7.8564 2.318 ...
  ## minutes: POSIXlt, format: NA NA NA
  </code></pre>
  
  <p>I need to convert the minute of day column to a date/time format:</p>
  
  <pre><code>minuteave$minutes &lt;- as.POSIXlt(as.character(minuteave$minuteofday), format="%m/%d/%Y %H:%M:%S")
  </code></pre>
  
  <p>I've tried <code>as.POSIXlt</code>, <code>as.POSIXct</code> and <code>as.Date</code>. None of which worked. Does anyone have ANY thoughts.</p>
  
  <p>The goal is to plot minutes vs. dDdt, but it won't let me plot in the specified time period that I want to as a factor. I have no idea what to try next...</p>