title: R interaction plot not showing the graph
body: <p>I tried to get an interaction plot.my code is,</p>
  
  <pre><code>hours=c(16.5,11.8,12.3,16.6,21.4,17.3,16.9,21.0)
  facA=factor(rep(c(1,2),c(4,4)))
  facB=factor(rep(gl(4,2),1))
  interaction.plot(facA, facB, hours)
  </code></pre>
  
  <p>And this what I got as the output.</p>
  
  <p><a href="https://i.stack.imgur.com/7WuHN.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/7WuHN.png" alt=""></a></p>
  
  <p>Can anyone help me to figure out what is wrong with me code? Thank you.</p>