title: ggplot2: control absolute plot size in R studio
body: <p>I am new to, but already love plotting with the <code>ggplot2</code> package. There is one issue I still do not know how to achieve: can I, somehow, set the absolute size of a plot in RStudio within a ggplot-command?
  I know, that I can</p>
  
  <ul>
  <li>adjust the relative size of the x- and y-axes via <code>theme (aspect.ratio)</code>.</li>
  <li>set the final absolute size of a plot when exporting via <code>ggsave (width, height)</code>.</li>
  </ul>
  
  <p>However, I'd wish to have a realistic preview of the plots I create within R-Studio, preferably in the plot-panel. Of course I could try and adjust the plot-panel size by eye - however, this is not very precise and not reproducable.</p>
  
  <p>The only working solution that I know is to open a new device with definde size (for example via <code>x11 (width = 3, height = 3)</code>). However, I'd prefer ommiting to open a new window.</p>
  
  <p>I can think of two options: </p>
  
  <ul>
  <li>programatically set the plot-panel size in R-Studio or</li>
  <li>set an absolute plot size which is only drawn if the plot-panel is
  large enough. </li>
  </ul>
  
  <p>For both, I have to admit that I don't know how to. For me, an optimal solution could be called as an argument within <code>ggplot ()</code>.</p>
  
  <p>Why is this important to me? --> a graph created in R-Studio might look quite nice, but when exported and shrinked to publication size, the text elements, axes and plot-content might look somewhat disproportional. Most of the time, the plots I create are bigger in R-Studio than my focal plot size.</p>