title: setdiff() function in R supposed to exclude numbers but it isn't
body: <p>So I am using <code>setdiff()</code> function for 2 vectors. As I understand if do</p>
  <pre><code>a &lt;- c(5,6,7)
  b &lt;- (5,7,9,10,11)
  </code></pre>
  <p><code>setdiff(a,b)</code> should give 6</p>
  <p>I am using one vector</p>
  <pre><code> sort(unique(probable_digit_matter_169))
   [1]  1  2  3  4  5  7  8  9 14 15 16 18 19 21 22 23 25 26 27 30 32 34 36 37 38 40 41 42 45 47 49 51 52 56 58 59 61 62 64 65
  </code></pre>
  <p>so <code>setdiff(c(4:68),unique(probable_digit_matter_169))</code> should give elements that are in <code>c(4:68)</code> but not in the <code>unique(probable_digit_matter_169)</code></p>
  <p>but the answer of</p>
  <pre><code>&gt; setdiff(c(4:68),sort(unique(probable_digit_matter_169)))
   [1]  6 10 11 12 13 17 20 21 22 23 24 25 28 29 31 33 35 39 43 44 46 48 49 50 51 52 53 54 55 57 60 63 66 67 68
  </code></pre>
  <p>as you can see several numbers are here which isn't supposed to be. 21, 22, 23, 25, 49, 51, 52 these numbers are in the vector so when I apply <code>setdiff()</code> they should be eliminated. What am I doing wrong ? I couldn't find answers elsewhere. Thank you for not being rude and helping me.</p>