title: Mapping different states with geom_sf using facet wrap and scales free
body: <p>First, I am aware of this answer : <a href="https://stackoverflow.com/questions/44814768/mapping-different-states-in-r-using-facet-wrap">Mapping different states in R using facet wrap</a><br>
  But I work with object of library <code>sf</code>.<br>
  It seems that <code>facet_wrap(scales = "free")</code> is not available for objects plotted with <code>geom_sf</code> in ggplot2. I get this message:</p>
  
  <blockquote>
    <p>Erreur : Free scales are only supported with <code>coord_cartesian()</code> and
    <code>coord_flip()</code></p>
  </blockquote>
  
  <p>Is there any option I have missed ?<br>
  Anyone has solve the problem without being forced to use <code>cowplot</code> (or any other gridarrange)?</p>
  
  <p>Indeed, here is an example. I would like to show the different French regions separately in facets but with their own x/y limits.</p>
  
  <h2>The result without scales = "free"</h2>
  
  <p>Scales are calculated with the extent of the entire map.</p>
  
  <pre><code>FRA &lt;- raster::getData(name = "GADM", country = "FRA", level = 1)
  FRA_sf &lt;- st_as_sf(FRA)
  
  g &lt;- ggplot(FRA_sf) +
    geom_sf() +
    facet_wrap(~NAME_1)
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/OKJDL.png" rel="noreferrer"><img src="https://i.stack.imgur.com/OKJDL.png" alt="facet regions with geom_sf"></a></p>
  
  <h2>The result using cowplot</h2>
  
  <p>I need to use a list of ggplots and can then combine them.
  This is the targeted output. It is cleaner. But I also want a clean way to add a legend. (I know may have a common legend like in this other SO question :
  <a href="https://stackoverflow.com/questions/44852114/facet-wrap-distorts-state-maps-in-r">facet wrap distorts state maps in R</a>)</p>
  
  <pre><code>g &lt;- purrr::map(FRA_sf$NAME_1,
             function(x) {
               ggplot() +
                 geom_sf(data = filter(FRA_sf, NAME_1 == x)) +
                 guides(fill = FALSE) +
                 ggtitle(x)
             })
  
  g2 &lt;- cowplot::plot_grid(plotlist = g)
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/8XcNI.png" rel="noreferrer"><img src="https://i.stack.imgur.com/8XcNI.png" alt="facet regions with geom_sf and cowplot"></a></p>