title: Map scale in GISTools package R
body: <p>I am trying to get a simple map for the Alpine region in R, using the libraries rworldmap and rworldxtra. I will then add points in the map for locating specific sites. </p>
  
  <p>For adding a north arrow and a map scale that look nicer I was trying the functions north.arrow() and map.scale() from the package 'GISTools'.
  I suppose this package was developed for US, and for drawing the scale it requires a transformation function from/to feet, and I cannot figure out how to make it working with the correct proportions...</p>
  
  <p>Here is the code: </p>
  
  <pre><code>library(rworldmap); library(rworldxtra); library(GISTools)
  newmap &lt;- getMap(resolution="high", projection=NA)
  plot(newmap, xlim=c(5.7,16.6), ylim=c(46,46), asp=1.5, col="gray90")
  north.arrow(xb=11.7, yb=45.4, len=0.1, lab="N",cex.lab=0.8,col='gray10')
  
  map.scale(10, 45,ft2km(10000),"Km", 4, 0.5) #here is the headache...
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/6GF3b.jpg" alt="It looks nice, but the proportions are not correct..."></p>