title: Week Number to Starting Date of Each Week in R
body: <p>A few questions have come close to what I am looking for, but I can't find one that gets it right on.</p>
  
  <p>I have sales data for several products for each day over a 6-year period.  I summed the data by week, starting January 1, 2008.  During the period 1/1/08-12/30/13, there were 313 weeks, so I just created dataframes for each product that contained columns for week numbers 1-313 and the weekly sales for each respective week.</p>
  
  <p>I am plotting them with ggplot2, adding trendlines, etc.</p>
  
  <p>The x-axis obviously uses the week number for its values, but I would prefer if it used the actual dates of the start of each week (Jaunary 1, 2008, a Tuesday, January 8, 2008, December 25, 2013, etc).</p>
  
  <p>What is the best way to do this?  How can I convert weeks 1-313 into their respective Start of Week dates?  Or, is there a way to override the axis values on the plot itself?</p>