title: connecting points
body: <p>I have the following plot</p>
  
  <pre><code>require(ggplot2)
  
  dtf &lt;- structure(list(Variance = c(5.213, 1.377, 0.858, 0.613, 0.412, 0.229, 0.139, 0.094, 0.064), Component = structure(1:9, .Label = c("PC1", "PC2", "PC3", "PC4", "PC5", "PC6", "PC7", "PC8", "PC9"), class = "factor")), .Names = c("Variance", "Component"), row.names = c(NA, -9L), class = "data.frame")
  
  ggplot(dtf, aes(x = Component, y = Variance)) +
  geom_point()
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/nJRle.png" alt="enter image description here"></p>
  
  <p>I would simply like to connect the dots with straight lines. I tried <code>+geom_line()</code> but that generated an error</p>