title: Bar Chart: How to choose color if value is positive vs value is negative
body: <p>I have a pandas dataframe with positive and negative values and want to plot it as a bar chart.</p>
  <p>I want to plot the positive colors 'green' and the negative values 'red' (very original...lol).</p>
  <p>I'm not sure how to pass if &gt; 0 'green' else &lt; 0 'red'?</p>
  <pre><code>data = pd.DataFrame([[-15], [10], [8], [-4.5]],
                      index=['a', 'b', 'c', 'd'],
                      columns=['values'])
  data.plot(kind='barh')
  </code></pre>
  <p><a href="https://i.stack.imgur.com/UwRdt.png" rel="noreferrer"><img src="https://i.stack.imgur.com/UwRdt.png" alt="bar plot" /></a></p>