title: ValueError: Invalid RGBA argument: 'o'
body: <p>I am trying to draw a scatter plot in Python with color code stored in 'color' column of dataframe. And I get invalid RGBA argument error.</p>
  
  <p>Here's my code and data:</p>
  
  <pre><code>df.plot.scatter(x='x', y='y', c='color')  
  
        id         x     type     color     y
  0    109       570.4       ha     r     500.8
  1    110       632.4       ha     r     567.2
  2    111       399.4       of     b     487.2
  3    112       250.2       of     b     444.4  
  </code></pre>
  
  <p>...</p>