title: How to define color of intersection in a Venn diagram?
body: <p>I found many resources on how to draw Venn diagrams in R. <a href="https://stackoverflow.com/questions/tagged/venn-diagram+r">Stack Overflow has a lot of them</a>. However, I still can't draw my diagrams the way I want. Take the following code as an example:</p>
  
  <pre><code>library("VennDiagram")
  
  A &lt;- 1:4
  B &lt;- 3:6
  d &lt;- list(A, B)
  
  vp &lt;- venn.diagram(d, fill = c("white", "white"), alpha = 1, filename = NULL, 
    category.names=c("A", "B"))
  grid.draw(vp)
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/8Lx7d.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/8Lx7d.png" alt="enter image description here"></a></p>
  
  <p>I want the intersection between the sets to be red. However, if I change any of the white colors to red, I get the following:</p>
  
  <pre><code>vp_red &lt;- venn.diagram(d, fill = c("red", "white"), alpha = 1, filename = NULL, 
    category.names=c("A", "B"))
  grid.draw(vp_red)
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/LEV2J.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/LEV2J.png" alt="enter image description here"></a></p>
  
  <p>That's not quite what I want. I want only the intersection to be red. If I change the alpha, this is what I get:</p>
  
  <pre><code>vp_alpha &lt;- venn.diagram(d, fill = c("red", "white"), alpha = 0.5, filename = NULL, 
    category.names=c("A", "B"))
  grid.draw(vp_alpha)
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/uIeIJ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/uIeIJ.png" alt="enter image description here"></a></p>
  
  <p>Now I have pink in my intersection. This is not what I want as well. What I want is something like this <a href="https://en.wikipedia.org/wiki/Intersection_(set_theory)" rel="nofollow noreferrer">image from Wikipedia</a>:</p>
  
  <p><a href="https://i.stack.imgur.com/scgyS.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/scgyS.png" alt="enter image description here"></a></p>
  
  <p>How can I do this? Maybe <code>VennDiagram</code> package can't do it and I need some other package, but I've been testing different ways to do it, and I'm not being able to find a solution.</p>