title: How to set ggplot2 font family
body: <p>I use R/RStudio on osx. The font family must to be set in the images that contains the unicode character. 
  e.g. <code>plot(1:10, 1:10, main="中文", sub="中文", family="宋体")</code> </p>
  
  <p>How to set <code>family="宋体"</code> in ggplot?</p>
  
  <p>The ggplot function I used:</p>
  
  <pre><code>ggplot(subset(v, s&gt;15157000), aes(x=V2, y=V5, group=V1,color=as.character(V1))) + 
      geom_line()
  </code></pre>