title: Aggregate daily level data to weekly level in R
body: <p>I have a huge dataset similar to the following reproducible sample data. </p>
  
  <pre><code>   Interval    value
  1  2012-06-10   552
  2  2012-06-11  4850
  3  2012-06-12  4642
  4  2012-06-13  4132
  5  2012-06-14  4190
  6  2012-06-15  4186
  7  2012-06-16  1139
  8  2012-06-17   490
  9  2012-06-18  5156
  10 2012-06-19  4430
  11 2012-06-20  4447
  12 2012-06-21  4256
  13 2012-06-22  3856
  14 2012-06-23  1163
  15 2012-06-24   564
  16 2012-06-25  4866
  17 2012-06-26  4421
  18 2012-06-27  4206
  19 2012-06-28  4272
  20 2012-06-29  3993
  21 2012-06-30  1211
  22 2012-07-01   698
  23 2012-07-02  5770
  24 2012-07-03  5103
  25 2012-07-04   775
  26 2012-07-05  5140
  27 2012-07-06  4868
  28 2012-07-07  1225
  29 2012-07-08   671
  30 2012-07-09  5726
  31 2012-07-10  5176
  </code></pre>
  
  <p>I want to aggregate this data to weekly level to get the output similar to the following:</p>
  
  <pre><code>   Interval           value
  1  Week 2, June 2012  *aggregate value for day 10 to day 14 of June 2012*
  2  Week 3, June 2012  *aggregate value for day 15 to day 21 of June 2012*
  3  Week 4, June 2012  *aggregate value for day 22 to day 28 of June 2012*
  4  Week 5, June 2012  *aggregate value for day 29 to day 30 of June 2012*
  5  Week 1, July 2012  *aggregate value for day 1 to day 7 of July 2012*
  6  Week 2, July 2012  *aggregate value for day 8 to day 10 of July 2012*
  </code></pre>
  
  <p>How do I achieve this easily without writing a long code? </p>