title: Avoid overlapping lines in a ggplot
body: <p>I want the lines in a ggplot to plot side by side. 
  So when two groups are having the same amount of cases on y axis I want both lines to be visible. adjusting Alpha is my last resort. I would rather want them to be plotted one over /under the other. Is there a way to do this?</p>
  
  <p>Here is an example:
  <a href="https://i.stack.imgur.com/QmiZs.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/QmiZs.png" alt="bad graph"></a></p>
  
  <p>I want the gold and red to be both visible...</p>
  
  <p>my code is basic ggplot with <code>geom_lines()</code> nothing fancy.</p>
  
  <pre><code>require(ggplot2,quietly = T)
  ggplot(tinnel_sum,aes(Czas,Tinnel,group=Grupa,color=Grupa))+
  geom_line(aes(y=jitter(Tinnel)))+
  ggtitle("Suma szczurów z pozytywnym objawem Tinella \n 
  w każdej z grup, w zależności od czasu dla całej grupy")+
  ylab("Liczba szczurów z pozytywnym objawem Tinella")+
  theme_bw(base_size = 12)
  </code></pre>
  
  <p>the <code>y</code> value is just an integer with values 0 - 12. which is a sum of observed cases. </p>
  
  <p>That is it. It's pretty straighforward.</p>
  
  <p>The jitter unfortunately adds unwanted curviness to lines that should otherwise be straight even if I set it to very low values <code>0.01</code> And I think there could be a better solution.</p>
  
  <p><a href="https://i.stack.imgur.com/9hnq2.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/9hnq2.png" alt="enter image description here"></a></p>