title: pandas barplot choose color for each variable
body: <p>I usually use matplotlib, but was playing with pandas plotting and experienced unexpected behaviour. I was assuming the following would return red and green edges rather than alternating. What am I missing here?</p>
  <pre><code>import pandas as pd
  import matplotlib.pyplot as plt
  df = pd.DataFrame({&quot;col1&quot;:[1,2,4,5,6], &quot;col2&quot;:[4,5,1,2,3]})
  
  def amounts(df):
      fig, ax = plt.subplots(1,1, figsize=(3,4))
      (df.filter(['col1','col2'])
         .plot.bar(ax=ax,stacked=True, edgecolor=[&quot;red&quot;,&quot;green&quot;],
                   fill=False,linewidth=2,rot=0))
      ax.set_xlabel(&quot;&quot;)
      plt.tight_layout()
      plt.show()
  
  amounts(df)
  </code></pre>