title: Combination Boxplot and Histogram using ggplot2
body: <p>I am trying to combine a histogram and boxplot for visualizing a continuous variable. Here is the code I have so far</p>
  
  <pre><code>require(ggplot2)
  require(gridExtra)
  p1 = qplot(x = 1, y = mpg, data = mtcars, xlab = "", geom = 'boxplot') + 
       coord_flip()
  p2 = qplot(x = mpg, data = mtcars, geom = 'histogram')
  grid.arrange(p2, p1, widths = c(1, 2))
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/zxZh1.png" alt="plot"></p>
  
  <p>It looks fine except for the alignment of the x axes. Can anyone tell me how I can align them?
  Alternately, if someone has a better way of making this graph using <code>ggplot2</code>, that would be appreciated as well.</p>