title: rename x-axis label so that coordinates are show as positive
body: <p>I am trying to use 'coord_sf' ( due to the need for the projection) with ggplot2. However, I can't change the labels on the x-axis and remove the <code>-</code> sign before the coordinates. I want to label the values in the x-axis as in this plot <a href="https://i.stack.imgur.com/LMsIZ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/LMsIZ.png" alt="enter image description here" /></a>
  (obtained without <code>coord_sf</code>).</p>
  <p>Sample data and code is below.</p>
  <pre><code>dts&lt;-structure(list(x = c(-119, -118, -117, -116, -115, -114, -113, 
  -112, -111, -110, -109, -108, -107, -106, -105, -104, -103, -102, 
  -101, -119, -118, -117, -116, -115, -114, -113, -112, -111, -110, 
  -109, -108, -107, -106, -105, -104, -103, -102, -101, -119, -118, 
  -117, -116, -115, -114, -113, -112, -111, -110, -109, -108, -107, 
  -106, -105, -104, -103, -102, -101, -119, -118, -117, -116, -115, 
  -114, -113, -112, -111, -110, -109, -108, -107, -106, -105, -104, 
  -103, -102, -101, -119, -118, -117, -116, -115, -114, -113, -112, 
  -111, -110, -109, -108, -107, -106, -105, -104, -103, -102, -101, 
  -119, -118, -117, -116, -115, -114, -113, -112, -111, -110, -109, 
  -108, -107, -106, -105, -104, -103, -102, -101, -119, -118, -117, 
  -116, -115, -114, -113, -112, -111, -110, -109, -108, -107, -106, 
  -105, -104, -103, -102, -101, -119, -118, -117, -116, -115, -114, 
  -113, -112, -111, -110, -109, -108, -107, -106, -105, -104, -103, 
  -102, -101), y = c(54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 
  54, 54, 54, 54, 54, 54, 54, 54, 53, 53, 53, 53, 53, 53, 53, 53, 
  53, 53, 53, 53, 53, 53, 53, 53, 53, 53, 53, 52, 52, 52, 52, 52, 
  52, 52, 52, 52, 52, 52, 52, 52, 52, 52, 52, 52, 52, 52, 51, 51, 
  51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 
  51, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 54, 
  54, 54, 54, 54, 53, 53, 53, 53, 53, 53, 53, 53, 53, 53, 53, 53, 
  53, 53, 53, 53, 53, 53, 53, 52, 52, 52, 52, 52, 52, 52, 52, 52, 
  52, 52, 52, 52, 52, 52, 52, 52, 52, 52, 51, 51, 51, 51, 51, 51, 
  51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51, 51), val = c(3.4, 
  3.6, 3.5, 3.4, 3.3, 3.3, 3.4, 3.4, 3.4, 3.4, 3.5, 3.5, 3.1, 3, 
  3.4, 3.6, 3.5, 3.1, 3.1, 3.5, 3.6, 3.7, 3.7, 3.5, 3.6, 3.5, 3.5, 
  3.5, 3.4, 3.3, 3.4, 3.4, 3.5, 3.5, 3.5, 3.7, 3.5, 2.9, 3.6, 3.6, 
  3.8, 3.8, 3.5, 3.4, 3.4, 3.5, 3.5, 3.5, 3.4, 3.4, 3.4, 3.4, 3.4, 
  3.3, 3.4, 3.5, 3.7, 3.3, 3.5, 3.7, 3.5, 3.5, 3.5, 3.6, 3.4, 3.4, 
  3.4, 3.4, 3.4, 3.2, 3.3, 3.3, 3.3, 3.4, 3.3, 3.4, -0.7, -0.7, 
  -0.7, -0.7, -0.7, -0.7, -0.7, -0.7, -0.7, -0.7, -0.7, -0.7, -0.7, 
  -0.6, -0.7, -0.7, -0.6, -0.6, -0.5, -0.7, -0.7, -0.8, -0.7, -0.7, 
  -0.7, -0.7, -0.7, -0.7, -0.7, -0.7, -0.7, -0.7, -0.7, -0.7, -0.7, 
  -0.7, -0.6, -0.5, -0.8, -0.8, -0.8, -0.8, -0.8, -0.8, -0.8, -0.8, 
  -0.8, -0.8, -0.8, -0.7, -0.7, -0.7, -0.7, -0.7, -0.7, -0.6, -0.6, 
  -0.8, -0.8, -0.8, -0.8, -0.8, -0.8, -0.8, -0.8, -0.8, -0.8, -0.8, 
  -0.8, -0.7, -0.7, -0.7, -0.7, -0.7, -0.6, -0.6)), row.names = c(NA, 
  -152L), class = c(&quot;tbl_df&quot;, &quot;tbl&quot;, &quot;data.frame&quot;))
  </code></pre>
  <p>Code. This code creates the plot but the labels in the x-axis are negative and I cannot change it to make positive. ANy help would be appreciated.</p>
  <pre><code>plt&lt;-ggplot(dts,aes(x=x,y=y))+
    geom_tile(aes(fill=val),alpha=1)+
    coord_sf(datum = st_crs(3978))+ #must keep this projection ( or how can i use EPSG::3978 with coord_map ?)
    xlab(&quot;Longitude (°W)&quot;)+
    ylab(&quot;Latitude (°N)&quot;)
    # scale_x_continuous(breaks = seq(-120,-100,2),
    #                    labels = seq(120,100,-2),
    #                    expand = c(0, 0))
  plt
  </code></pre>