title: Possible to subscript or change vertex shapes in igraph?
body: <p>I am visualising a network that of data with three groups, an individual person plus their corresponding company and position. There are differing companies plus positions within the database. I wish to format the figure for publication, so need to print in greyscale. However, I need a method of discriminating one individual from another, according to position and company. I thought a subscript containing a numeric ID for each individual may work. </p>
  
  <p>However, is it possible to subscript part of a vertex label in igraph?</p>
  
  <p>I know the following works for base plots, but what about igraph?</p>
  
  <p><code>plot(1,1, main=expression('title'^2))</code></p>
  
  <p>Another option could be to assign a different shape to each individual however, I am unsure of how to do this.</p>