title: Count by group across multiple columns
body: <p>My dataset looks like this:</p>
  <pre><code>Names       Sample   Init_QC  Run_QC
  A             DN      PASS     PASS
  A             DN      FAIL     PASS
  A             RN      FAIL     FAIL
  B             DN      PASS     FAIL
  B             DN      PASS     PASS
  B             RN      FAIL     PASS
  C             DN      PASS     FAIL
  C             DN      FAIL     FAIL
  C             RN      PASS     PASS
  </code></pre>
  <p>I am looking to have things summarized by &quot;Names&quot; by counting number of occurrences of each category. Result would look like this:</p>
  <pre><code>Names   DN  RN   Init_QC$PASS  Init_QC$FAIL   Run_QC$PASS   Run_QC$FAIL
   A      2    1       1              2             2              1
   B      2    1       2              1             2              1
   C      2    1       1              2             1              2
  </code></pre>
  <p>I was hoping to use &quot;table&quot; or &quot;count&quot; from dplyr but without success</p>
  <p>Would anyone have an easy way to do this ?
  Thanks very much</p>