title: how to define facet axis limits in ggpairs function
body: <p>Having a <code>ggpairs</code> function, how would one limit range of lower facets to e.g. 0.5 for x and y?</p>
  
  <pre><code>library(GGally)
  
  xy &lt;- data.frame(matrix(runif(4 * 1000), ncol = 4))
  
  ggpairs(xy)
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/GzwHO.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/GzwHO.png" alt="enter image description here"></a></p>