title: How to pass data and aesthetics across ggplot2 functions
body: <p>I have to create a figure with ggplot2 that has roughly this structure:</p>
  
  <pre><code>p &lt;- ggplot() +
          geom_rect(data = regions,aes(xmin = xmin, xmax = xmax, ymin = -Inf, ymax = Inf), 
                    fill = "yellow",alpha = 0.1) + 
      geom_line(data = data, aes(x=dt, y = y, color = case))  +
      geom_point(data = data, aes(x=dt, y = y, color = case)) +
      facet_grid(groups ~ ., scale="free_y")
      geom_vline(x=as.numeric(dates_start), color = "orange3",linetype="dashed") + 
      geom_vline(x=as.numeric(dates_end), color = "orange3",linetype="dashed")
  
  p
  </code></pre>
  
  <p>Is there anyway I can avoid having to pass all the details in <code>geom_point</code>? since they are the same as the one used in <code>geom_line</code>?</p>