title: ggplot map fill with gradient color
body: <p>I am filling <code>ggplot + geom_sf</code> with colors. Most values (<code>value_pop</code>) in my data are between 1-30, with very few outliers reaching values of up to 350.</p>
  
  <p>My code looks like this</p>
  
  <pre><code>ggplot(df, aes(fill=value_pop))+
    geom_sf()+
    scale_fill_gradientn(colours=rev(brewer.pal(6,"RdYlBu")),
                         name="Susirgimai\n/100.000 gyventojų",
                         na.value = "grey100", 
                         values =  rescale(seq(0, 400, length.out = 6)))
  </code></pre>
  
  <p>What I would like to have is a following scale/legend and accordingly the coloring of the map</p>
  
  <p><a href="https://i.stack.imgur.com/HVYTE.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/HVYTE.png" alt="enter image description here"></a></p>
  
  <p>, so I would see the variation of lower values in the map, but my code yields</p>
  
  <p><a href="https://i.stack.imgur.com/lWN6P.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/lWN6P.png" alt="enter image description here"></a></p>
  
  <p>Any suggestions on how to change the <code>scale_fill_gradientn(...)</code> parameters, so that I can set manually the values? I would rather not cut my <code>value_pop</code> into groups, but leave it numerical.
  Thanks a lot</p>