title: if statemtent with error I never seen
body: <p>I don't understand this error: </p>
  
  <pre><code>Warning message:
  In if ((t$carried2 == t$Dead5) &amp; (t$carried2 == t$Dead6)) { :
    the condition has length &gt; 1 and only the first element will be used
  </code></pre>
  
  <p>my piece of code:</p>
  
  <pre><code>if ((t$carried2 == t$Dead5) &amp; (t$carried2 == t$Dead6)) {(t$Dead5 = 0) &amp; (t$Dead6 = 0)}
  </code></pre>
  
  <p>This is probably crappy, but I am new. Anyways, I want to say if (this and that happen) {then this and that = 0</p>