title: group and sum multiple variables R
body: <p>I have a somewhat simple question (i think), but can't seem to find a solution. I would like to create a new dataframe that groups and sums multiple variables. </p>
  
  <p>My data:</p>
  
  <pre><code>ID  Test    result  ped adult
  AB  a   0   0   1
  AB  b   1   0   1
  FM  a   1   1   0
  FM  c   0   1   0
  WD  a   0   0   1
  WD  b   1   0   1
  WD  c   0   0   1
  WD  d   1   0   1
  WD  a   0   0   1
  WD  a   1   0   1
  </code></pre>
  
  <p>The output I would like:</p>
  
  <pre><code>Test    No of ID's test with test performed     No of ID's positive     ped adult
  a   3   2   1   1
  b   2   2   0   2
  c   2   0   0   0
  d   1   1   0   1
  </code></pre>
  
  <p>I have tried using aggregate and dplyr using group_by and sum, but have not had success.</p>
  
  <p>NB: edited to add ped and adult columns. I would like to sum the positive tests and then have a sum for ped and adult positive tests. </p>