title: ggplot2 bar plot, no space between bottom of geom and x axis keep space above
body: <p>When I plot a bar graph in ggplot2 I would like to reduce the space between the bottom of the bars and the x-axis to 0, yet keep the space above the bars and the plot box.  I have a hack to do it below.  It's dirty and I want to be clean again.  Is there a way to achieve this behavior without the dirty little hack?</p>
  
  <p><strong>Default (desired space above but don't want space below bars):</strong></p>
  
  <pre><code>ggplot(mtcars, aes(x=as.factor(carb))) + 
      geom_bar()
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/avtvl.png" alt="enter image description here"></p>
  
  <p><strong>Use expand (undesired 0 space above but got the 0 space below bars):</strong></p>
  
  <pre><code>ggplot(mtcars, aes(x=as.factor(carb))) + 
      geom_bar() + 
      scale_y_continuous(expand = c(0,0)) 
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/zbWSy.png" alt="enter image description here"></p>
  
  <p><strong>Dirty Hack (I like it but its.. well, dirty):</strong></p>
  
  <pre><code>ggplot(mtcars, aes(x=as.factor(carb))) + 
      geom_bar() + 
      scale_y_continuous(expand = c(0,0)) +
      geom_text(aes(x=1, y=10.3, label="Stretch it"), vjust=-1)
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/ZI00w.png" alt="enter image description here"></p>