title: Showing all x axis label for discrete variable in ggplot bar plot
body: <p>I have a set of data and I want to plot a bar plot for the data. The example of data is shown below:</p>
  <pre><code>   yq        flag      n ratio
     &lt;yearqtr&gt; &lt;fct&gt; &lt;int&gt; &lt;dbl&gt;
   1 2011 Q1   0       269 0.610
   2 2011 Q1   1       172 0.390
   3 2011 Q2   0       266 0.687
   4 2011 Q2   1       121 0.313
   5 2011 Q3   0       239 0.646
   6 2011 Q3   1       131 0.354
   7 2011 Q4   0       153 0.668
   8 2011 Q4   1        76 0.332
   9 2012 Q1   0       260 0.665
  10 2012 Q1   1       131 0.335
  11 2012 Q2   0       284 0.676
  12 2012 Q2   1       136 0.324
  13 2012 Q3   0       197 0.699
  14 2012 Q3   1        85 0.301
  15 2012 Q4   0       130 0.688
  16 2012 Q4   1        59 0.312
  17 2013 Q1   0       273 0.705
  18 2013 Q1   1       114 0.295
  19 2013 Q2   0       333 0.729
  20 2013 Q2   1       124 0.271
  </code></pre>
  <p>What I want to do is basically plotting the ratio for each flag in each quarter. I wrote the code below:</p>
  <pre><code>data$flag &lt;- as.factor(data$flag)
  ggplot(data=data, aes(x=yq, y=ratio, fill=flag)) +
    geom_bar(stat=&quot;identity&quot;, color=&quot;black&quot;, position=position_dodge())+
    theme_minimal() +
    scale_fill_manual(values=c('#999999','#E69F00'))
  </code></pre>
  <p>The result is shown below:</p>
  <p><a href="https://i.stack.imgur.com/uxWx8.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/uxWx8.png" alt="result of code" /></a></p>
  <p>But what I actually want is to show all quarters on the x-axis and maybe in vertical form for better visualization. I tried using <code>scale_x_discrete(limits=yq)</code> however, this is not the correct answer and return an error. How can I do this?</p>