title: igraph plot graph with vertex size dependent on betweenness centrality
body: <p>I would like the size of the nodes in the graph to be dependent on the calculated betweenness centrality of the vertices. How can this be done?</p>
  
  <p>My current code is below:</p>
  
  <pre><code>require(igraph)
  g &lt;- read.graph("data.graphml", "graphml")
  plot(g,vertex.size = x,layout = layout.fruchterman.reingold)
  </code></pre>
  
  <p>How can I set 'x' to be a vertex size that is dependent on the betweeness centrality of a node?</p>