title: When using ggplot2, can I set the color of histogram bars without potentially obscuring low values?
body: <p>When calling <code>geom_histogram()</code> with the <code>color</code>, and <code>fill</code> arguments, <code>ggplot2</code> will confusingly paint the whole x-axis range, making it impossible to visually distinguish between a low value and a zero value.</p>
  
  <p>Running the following code:</p>
  
  <pre><code>ggplot(esubset, aes(x=exectime)) + geom_histogram(binwidth = 0.5) +
  theme_bw() + scale_x_continuous(breaks=seq(0,20), limits=c(0,20))
  </code></pre>
  
  <p>will result in</p>
  
  <p><img src="https://i.stack.imgur.com/NSfMz.png" alt="a histogram w/o color attributes"></p>
  
  <p>This is visually very unappealing. To fix that, I'd like to instead use</p>
  
  <pre><code>ggplot(esubset, aes(x=exectime)) + geom_histogram(binwidth = 0.5,
  colour='black', fill='gray') + theme_bw() +
  scale_x_continuous(breaks=seq(0,20), limits=c(0,20))
  </code></pre>
  
  <p>which would result in</p>
  
  <p><img src="https://i.stack.imgur.com/MZBEB.png" alt="a histogram with color attributes"></p>
  
  <p>The problem is that I'll have no way of distinguishing whether <code>exectime</code> contains values past 10, as a few occurrences of 12, for example, would be hidden behind the horizontal line spanning the whole x-axis.</p>