title: comfortable way to use unicode characters in a ggplot graph
body: <p>Is there a good practice to insert unicode characters in a ggplot title and also save it as pdf?</p>
  
  <p>I am struggling with expression, paste and sprintf to get a nice title...</p>
  
  <p>So, what works is</p>
  
  <pre><code>ggtitle(expression(paste('5', mu, 'g')))
  </code></pre>
  
  <p>This will print an ugly greek mu. By ugly I mean a different font, but overall, it will be printed as pdf without problems. But the problems start, if you want to have new lines in the title. Or maybe I didn't found a solution for this.</p>
  
  <p>My preferred solution would be to use sprintf with the unicode number, so for example</p>
  
  <pre><code>ggtitle(sprintf('5\u03BCg'))
  </code></pre>
  
  <p>It shows a nice result on the screen but it is not possible to save as pdf with ggsave. PNG works fine, but I would like to use the pdf save option.</p>
  
  <p>Is there a possibility to plot the unicode characters with ggsave? I read about the cairo_pdf device, but this messes up the fonts and I can not save the plot properly.</p>
  
  <p>Thanks in advance for any help.</p>
  
  <p><strong>EDIT:</strong>
  <a href="http://www.staff.uni-mainz.de/madejung/test.pdf" rel="noreferrer">Example PDF</a></p>
  
  <p>I just uploaded an example PDF... So maybe my problem is somewhere else...</p>