Creating dummy variables
The lubridate package provides functions to easily convert character strings into dates in a sensible way. For example, the dmy function can parse strings in a variety of formats so long as the string is in the order of day-month-year. The lubridate functions handle all sorts of separators and extraneous characters.
As for your dummy variable, after you convert your v584 column into dates, just create a new column:
new_column &lt;- as.integer(v584 &gt; dmy(&quot;Sunday 29th May 2005&quot;))