title: R barplot axis scaling
body: <p>I want to plot a barplot of some data with some x-axis labels but so far I just keep running into the same problem, as the axis scaling is completely off limits and therefore my labels are wrongly positioned below the bars.
  The most simple example I can think of:</p>
  
  <pre><code>x = c(1:81)
  barplot(x)
  axis(side=1,at=c(0,20,40,60,80),labels=c(20,40,60,80,100))
  </code></pre>
  
  <p>As you can see, the x-axis does not stretch along the whole plot but stops somewhere in between. It seems to me as if the problem is quite simple, but I somehow I am not able to fix it and I could not find any solution so far :(</p>
  
  <p>Any help is greatly appreciated.</p>