title: Is there a more elegant way to convert two-digit years to four-digit years with lubridate?
body: <p>If a date vector has two-digit years, <code>mdy()</code> turns years between 00 and 68 into 21st Century years and years between 69 and 99 into 20th Century years. For example:</p>
  
  <pre><code>library(lubridate)    
  mdy(c("1/2/54","1/2/68","1/2/69","1/2/99","1/2/04"))
  </code></pre>
  
  <p>gives the following output:</p>
  
  <pre><code>Multiple format matches with 5 successes: %m/%d/%y, %m/%d/%Y.
  Using date format %m/%d/%y.
  [1] "2054-01-02 UTC" "2068-01-02 UTC" "1969-01-02 UTC" "1999-01-02 UTC" "2004-01-02 UTC"
  </code></pre>
  
  <p>I can fix this after the fact by subtracting 100 from the incorrect dates to turn 2054 and 2068 into 1954 and 1968. But is there a more elegant and less error-prone method of parsing two-digit dates so that they get handled correctly in the parsing process itself?</p>
  
  <p><strong>Update:</strong> After @JoshuaUlrich pointed me to <code>strptime</code> I found <a href="https://stackoverflow.com/questions/9508747/r-adding-century-to-year">this question</a>, which deals with an issue similar to mine, but using base R. </p>
  
  <p>It seems like a nice addition to date handling in R would be some way to handle century selection cutoffs for two-digit dates within the date parsing functions. </p>