title: Using r to read elements of a 2 column vector and return matches with corresponding 1st col name
body: <p>I need to take a two column vector in r. In the first column I have dates, 12/21/2011 format and I have a number in the second column, 255 format.</p>
  
  <p>I need to take a number of my choosing say 255 and see if it matches any numbers in my second column.  If it does match I need to return the date it matched on.</p>
  
  <p>I know about match, count, in etc. I just cannot seem to put it together.  I am a newbie perhaps this is a bit beyond my ability but I figure that if I learn something I'll be that much better for it.</p>
  
  <p>There are some partial matches in the questions but nothing as detailed as what I want.</p>
  
  <p>If anyone has any examples that will teach me I'd be more than happy.  If you have a reference in a book I will do that myself if you tell me the reference.</p>
  
  <p>Thank you very much. I'm using R 2.13.1 in a Windows XP SP3 environment.</p>