title: Summing up Certain Sequences of a Dataframe in R
body: <p>I have several data frames of daily rates of different regions by age-groups:</p>
  <pre><code>Date         0-14 Rate     15-29 Rate  30-44 Rate   45-64 Rate 65-79 Rate  80+ Rate   
  2020-23-12     0              33.54      45.68       88.88        96.13      41.28 
  2020-24-12     0              25.14      35.28       66.14        90.28      38.41
  </code></pre>
  <p>It begins on Wednesday (2020-23-12) and I have data from then on up to date.</p>
  <p>I want to obtain weekly row sums of rates from each Wednesday to Tuesday.</p>
  <p>There should be a wise way of combinations with aggregate, seq and rowsum functions to do this using a few lines. Otherwise, I'll use too long ways to do this.</p>