title: Format X-axis labels in ggplot
body: <p>I am using <code>ggplot</code> to draw the "score vs memberID" distribution of the following dataframe. "memberID"s are ordered in the descending order of "Score"</p>
  
  <p>In my real dataset I have 1000 member IDs and when I use the same code, x - axis labels are not visible. I just want to get a few of the labels visible (e.g., every 50th). Since I order the member IDs in descending order of scores I am not sure how to get only a few x-axis labels.</p>
  
  <p>Could someone help me in this matter pls.</p>
  
  <pre><code>test &lt;- read.table(text=" memberID SCORETYPE     Score
   0   score.1 0.7123645
   1   score.1 0.4893589
   2   score.1 0.6294229
   3   score.1 0.6051377
   4   score.1 0.1411411
   5   score.1 0.5173978
   6   score.1 0.5355791
   7   score.1 0.5946272
   8   score.1 0.1328829
   9   score.1 0.2012012
   10   score.2 0.6624559
   1   score.2 0.5306829
   2  score.2 0.5723985
   3   score.2 0.1839339
   4   score.2 0.5883927
   5   score.2 0.6020042
   6   score.2 0.6098381
   7   score.2 0.4739522
   8   score.2 0.4430409
   9   score.2 0.5831375
   10  score.2 0.2531375
    " ,header = TRUE)
  
  plottest &lt;- ggplot(data=test,aes(x=reorder(memberID,-Score),Score,group=SCORETYPE,colour=SCORETYPE))+geom_point()+geom_line()+xlab("User")
  plottest &lt;- plottest+theme(text = element_text(size=10),axis.text.x = element_text(angle = 90, hjust=0,size=10),legend.text=element_text(size=10))
  plottest &lt;- plottest + theme(axis.line.x = element_line(color="black", size = 1),axis.line.y = element_line(color="black", size = 1))
  plottest
  </code></pre>
  
  <p>This image is what I get from the example
  <a href="https://i.stack.imgur.com/2ipmg.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/2ipmg.png" alt="enter image description here"></a></p>
  
  <p>This image is what I get for my real data. I only want to display a few axis labels in here
  <a href="https://i.stack.imgur.com/J2zNw.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/J2zNw.png" alt="enter image description here"></a></p>