title: ValueError: 'vertices' must be a 2D list or array with shape Nx2
body: <p>I'm trying to animate a scatterplot but get the following error. I had it working previously but its now returning this error on repeat.</p>
  
  <pre><code>ValueError: 'vertices' must be a 2D list or array with shape Nx2
  </code></pre>
  
  <p>I'll attach the animation code below. I had it working before so know it works. </p>
  
  <pre><code>import matplotlib.pyplot as plt
  import matplotlib.animation as animation
  import numpy as np
  import matplotlib.transforms as transforms
  
  XA = np.random.randint(80, size=(1000, 15))
  YA = np.random.randint(80, size=(1000, 15)) 
  
  XB = np.random.randint(80, size=(1000, 15))
  YB = np.random.randint(80, size=(1000, 15)) 
  
  XC = np.random.randint(80, size=(1000, 1))
  YC = np.random.randint(80, size=(1000, 1))
  
  fig, ax = plt.subplots(figsize = (10,6))
  ax.axis('equal')
  
  '''' Scatter Plot  '''
  
  scatter_A = ax.scatter(XA[0], YA[0], c=['blue'], alpha = 0.7, s = 20, edgecolor = 'black', zorder = 2)
  scatter_B = ax.scatter(XB[0], YB[0], c=['white'], alpha = 0.7, s = 20, edgecolor = 'black', zorder = 2)
  
  offset = lambda p: transforms.ScaledTranslation(p/82.,0, plt.gcf().dpi_scale_trans)
  trans = plt.gca().transData
  scatter_C = ax.scatter(XC[0], YC[0], c=['red'], marker = 'o', alpha = 0.7, s = 10, edgecolor = 'black', zorder = 2,transform=trans+offset(+2))
  
  '''Animate Function '''
  
  def animate(i) :
      scatter_A.set_offsets([[[[[[[[[[[[[[[XA[0+i][0], YA[0+i][0]], [XA[0+i][1], YA[0+i][1]], [XA[0+i][2], YA[0+i][2]], [XA[0+i][3], YA[0+i][3]], [XA[0+i][4], YA[0+i][4]],[XA[0+i][5], YA[0+i][5]], [XA[0+i][6], YA[0+i][6]], [XA[0+i][7], YA[0+i][7]], [XA[0+i][8], YA[0+i][8]], [XA[0+i][9], YA[0+i][9]], [XA[0+i][10], YA[0+i][10]], [XA[0+i][11], YA[0+i][11]], [XA[0+i][12], YA[0+i][12]], [XA[0+i][13], YA[0+i][13]], [XA[0+i][14], YA[0+i][14]]]]]]]]]]]]]]]])
      scatter_B.set_offsets([[[[[[[[[[[[[[[XB[0+i][0], YB[0+i][0]], [XB[0+i][1], YB[0+i][1]], [XB[0+i][2], YB[0+i][2]], [XB[0+i][3], YB[0+i][3]], [XB[0+i][4], YB[0+i][4]],[XB[0+i][5], YB[0+i][5]], [XB[0+i][6], YB[0+i][6]], [XB[0+i][7], YB[0+i][7]], [XB[0+i][8], YB[0+i][8]], [XB[0+i][9], YB[0+i][9]], [XB[0+i][10], YB[0+i][10]], [XB[0+i][11], YB[0+i][11]], [XB[0+i][12], YB[0+i][12]], [XB[0+i][13], YB[0+i][13]], [XB[0+i][14], YB[0+i][14]]]]]]]]]]]]]]]])
      scatter_C.set_offsets([[XC[0+i][0], YC[0+i][0]]])
  
  
  ani = animation.FuncAnimation(fig, animate, np.arange(0,1000),
                                interval = 100, blit = False)
  
  
  Writer = animation.writers['ffmpeg']
  writer = Writer(fps = 10, bitrate = 8000)
  
  ax.autoscale()
  
  plt.draw()
  </code></pre>
  
  <p>I am running <code>Spyder 3.1.2</code> through <code>Anaconda 1.6.4</code>, <code>Python 3.5</code>, <code>Python 5.1.0</code></p>