title: How do i remove dash(-) in R?
body: <p>I'm very new to r. How should I make r read dash(-) or skip it and calculate average of No. of plant(last column).</p>
  
  <pre><code>Genotype Rep    No. of plant
  184  1   8
  7    1   7
  98   1   -
  101  2   7
  X    2   8
  62   2   -
  24   3   3
  30   3   4
  78   3   8
  119  3   8
  </code></pre>