title: Tick labels in ggplot2 bar graph
body: <p>I have a simple dataframe, <em>by_day</em>, that I'd like to plot out:</p>
  
  <pre><code> X weekday         variable value
  0       0 Number_of_tweets  5820
  1       1 Number_of_tweets  6965
  2       2 Number_of_tweets  7415
  3       3 Number_of_tweets  6800
  4       4 Number_of_tweets  5819
  5       5 Number_of_tweets  1753
  6       6 Number_of_tweets  1137
  </code></pre>
  
  <p>I can get the basic plot without any problem.</p>
  
  <pre><code>daily_plot &lt;- ggplot(data=by_day, aes(x=by_day$weekday, y=by_day$value)) + 
    geom_bar(stat = "identity") 
  </code></pre>
  
  <p>The issue comes when I try to modify the value labels. If I do this I end up with extra space on the right-hand side of the x-axis:</p>
  
  <pre><code>daily_plot + 
    scale_x_discrete("Day of the Week", breaks = c("0","1","2","3","4","5","6"), labels=c("Mon","Tues","Wed","Th","Fri","Sat","Sun"))
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/LpiET.png" alt="enter image description here"></p>
  
  <p>And if I do this, then the issue is the bars and the new labels are offset</p>
  
  <pre><code>daily_plot + 
    scale_x_discrete("Day of the Week", breaks = c("0","1","2","3","4","5","6"),    labels=c("Mon","Tues","Wed","Th","Fri","Sat","Sun"), limits=c("0","1","2","3","4","5","6")) + 
    theme(axis.title.x = element_text(vjust=-0.5), axis.title.y=element_text(vjust=0.1)) 
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/GCHw6.png" alt="enter image description here"></p>
  
  <p>I've spent some good time going over the ggplot2 documentation as well as StackOverflow but can't find the same issue. Any help would be appreciated.</p>