title: Can not create vertical labels using ggplot
body: <p>using following code, I can get labels using geom_text but they are not vertical, even after I change angle to 90.</p>
  
  <pre><code> p1 &lt;- ggplot(segment(p)) +
           geom_segment(aes(x=x,y=y,xend=xend,yend=yend),colour="blue") + labs(y = "Label y") +
           theme_classic()+theme(axis.line.x=element_blank(), axis.text.x=element_blank(), axis.ticks.x=element_blank(),axis.title.x=element_blank()) + 
           geom_text(data=leaf_label_data, aes(x=xend, y=yend,label=label,angle = 90))
  </code></pre>