title: How to make graphics with transparent background in R using ggplot2?
body: <p>I need to output ggplot2 graphics from R to PNG files with transparent background. Everything is ok with basic R graphics, but no transparency with ggplot2:</p>
  
  <pre><code>d &lt;- rnorm(100) #generating random data
  
  #this returns transparent png
  png('tr_tst1.png',width=300,height=300,units="px",bg = "transparent")
  boxplot(d)
  dev.off()
  
  df &lt;- data.frame(y=d,x=1)
  p &lt;- ggplot(df) + stat_boxplot(aes(x = x,y=y)) 
  p &lt;- p + opts(
      panel.background = theme_rect(fill = "transparent",colour = NA), # or theme_blank()
      panel.grid.minor = theme_blank(), 
      panel.grid.major = theme_blank()
  )
  #returns white background
  png('tr_tst2.png',width=300,height=300,units="px",bg = "transparent")
  p
  dev.off()
  </code></pre>
  
  <p><strong>Is there any way to get transparent background with ggplot2?</strong></p>