title: Invalid RGBA argument in matplotlib(python)
body: <p>i just read csv and i want to plot3d by scatter3d.</p>
  
  <pre><code>import matplotlib.pyplot as plt
  
  fig = plt.figure()
  ax = plt.axes(projection='3d')
  #ax.scatter3D(f2, f3, f1,'r')
  ax.scatter3D(features[1:22,3], features[1:22,4], features[1:22,5],'r',cmap='viridis')
  </code></pre>
  
  <p>but..</p>
  
  <pre><code>ValueError: Invalid RGBA argument: masked_array(data=[0.12156862745098039, 0.4666666666666667,
                     0.7058823529411765, 0.378827099272238],
               mask=False,
         fill_value='?',
              dtype=object)
  </code></pre>
  
  <p>comes out...
  it looks like the data was,</p>
  
  <pre><code>data=[0.12156862745098039, 0.4666666666666667, 0.7058823529411765, 0.378827099272238]
  </code></pre>
  
  <p>which is made by pandas...</p>
  
  <p>why the error comes out? I can not understand...
  the data is float and 1048575 rows × 1 columns in each features[:,3] or features[:,4]. 
  May be the size is too big?? 
  I tried [1:22,3] but nothing changed...</p>