title: create floating pie charts with ggplot
body: <p>Currently I am working on report with a floating pie chart as one of the plots. Currently I use the plotrix package to plot this pie chart. But since I use ggplot2 for all the other plots, the pie plot looks different. So I'm trying to create the plot using ggplot2. Currently I have two issues:</p>
  
  <ol>
  <li><p>The ggplot pie charts are plotted on a polar coordination system. I want to plot multiple pie charts on Cartesian coordination system. At the moment I do not know how to do this.</p></li>
  <li><p>I want to be able to control the pie radius on the Cartesian coordination system. </p></li>
  </ol>
  
  <p>Here is the code I currently use:</p>
  
  <pre><code>library("plotrix")
  plot(1:5, type="n", xlab="x", ylab="y")
  floating.pie(2, 3, c(1,3,5), radius=0.5)
  floating.pie(4, 2, c(2,4), radius=0.2)
  floating.pie(4.5, 4, c(3,2,5,1), radius=0.3)
  </code></pre>
  
  <p>Thanks for your time and help.</p>