title: Save plot with a given aspect ratio
body: <p>I'm working with the really awesome library ggplot2. I figured out how to set the aspect ratio of a plot by using <code>coord_fixed</code>. Now, I'd like to save the plot to a PDF with a specified width (e.g 10 cm) and let required height get calculated. I did not figure out how to achieve this. Is this even possible?</p>