title: How to create a network chart?
body: <p>I am trying to use <code>networkD3::forceNetwork</code> to create a chart of employers and colleges from which employers hire employees.</p>
  
  <p>Right now, I have something like this:</p>
  
  <pre><code>forceNetwork(Links= Links, Nodes= netDf , 
               Source = 'collegeName', Target = 'organizationName', Value='count',
               NodeID = 'collegeName', Group = 'organizationName')
  </code></pre>
  
  <p>But the output doesn't look as expected. What I would like to have, is:</p>
  
  <ol>
  <li>One bubble for each college
  
  <ol start="2">
  <li>One bubble for each employer</li>
  <li>Colleges connected to employer, with number of employers (<code>count</code>) mapped to the width of the connection lines.  </li>
  </ol></li>
  </ol>
  
  <p>Colleges are never connected to each other, and the same holds for employers.</p>
  
  <p>This is the dataset I am using <code>netDf</code>:</p>
  
  <pre><code> structure(list(collegeName = c("college1", "college1", "college2", 
  "college3", "college3", "college3", "college4", "college5", "college5", 
  "college6", "college6", "college6", "college7", "college7", "college7", 
  "college8", "college9", "college10", "college10", "college11"
  ), organizationName = c("employer2", "employer3", "employer2", 
  "employer1", "employer2", "employer3", "employer2", "employer2", 
  "employer3", "employer1", "employer2", "employer3", "employer1", 
  "employer2", "employer3", "employer2", "employer2", "employer2", 
  "employer3", "employer2"), count = c(858, 176, 461, 201, 2266, 
  495, 430, 1992, 290, 127, 1754, 549, 136, 2839, 686, 638, 275, 
  1388, 387, 188), group = c(2, 3, 2, 1, 2, 3, 2, 2, 3, 1, 2, 3, 
  1, 2, 3, 2, 2, 2, 3, 2)), .Names = c("collegeName", "organizationName", 
  "count", "group"), row.names = c(NA, -20L), class = "data.frame")
  </code></pre>
  
  <p>And this is the <code>Links</code> dataset:</p>
  
  <pre><code>structure(list(collegeName = c(0, 0, 1, 2, 2, 2, 3, 4, 4, 5, 
  5, 5, 6, 6, 6, 7, 8, 9, 9, 10), organizationName = c(1, 2, 1, 
  0, 1, 2, 1, 1, 2, 0, 1, 2, 0, 1, 2, 1, 1, 1, 2, 1), count = c(858, 
  176, 461, 201, 2266, 495, 430, 1992, 290, 127, 1754, 549, 136, 
  2839, 686, 638, 275, 1388, 387, 188), group = c(2, 3, 2, 1, 2, 
  3, 2, 2, 3, 1, 2, 3, 1, 2, 3, 2, 2, 2, 3, 2)), .Names = c("collegeName", 
  "organizationName", "count", "group"), row.names = c(NA, -20L
  ), class = "data.frame")
  </code></pre>
  
  <p>Also, would it be possible to map a 4th variable to the bubble size? Say for instance that I want to map <code>count</code> to che size of the bubble pertaining the employees, how can I do that?</p>