title: Matplotlib scatter now takes three arguments?
body: <p>I wrote a short script to display some graphs:</p>
  
  <pre><code>if __name__=='__main__':
      p1 = gen_spiral(label=0, dt=0,     n_samples=100, )
      p2 = gen_spiral(label=1, dt=np.pi, n_samples=100, )
      print ("Array:   {}\nType:   {}\nShape:   {}\nLength:   {}\nData:   {}\n".format("p1",   type(p1),   str(np.shape(p1)),   len(p1),    str(p1)))
      print ("Array:   {}\nType:   {}\nShape:   {}\nLength:   {}\nData:   {}\n".format("p2",   type(p2),   str(np.shape(p2)),   len(p2),    str(p2)))
  
  
      a = np.arange(1,20,1) 
      b = np.arange(1,20,1) 
      c = np.arange(0.0, 2.0, 0.01)
      d = np.sin(2*np.pi*c)
  
      fig1 = plt.figure()
      ax1 = fig1.add_subplot(121)
      ax1.scatter(a,b) 
      ax2 = fig1.add_subplot(122)
      ax2.scatter(c,d) 
  </code></pre>
  
  <p>and it worked fine. However, when I changed the function to display MY data: </p>
  
  <pre><code>fig1 = plt.figure()
  ax1 = fig1.add_subplot(121)
  ax1.scatter(p1)
  </code></pre>
  
  <p>It gave me an error that shouldn't exist:</p>
  
  <pre><code>Traceback (most recent call last):
    File "Theano--PlotSet--ME01.py", line 53, in &lt;module&gt;
      ax1.scatter(p1) 
  TypeError: scatter() takes at least 3 arguments (2 given)
  </code></pre>
  
  <p>That's not true: Scatter takes 3 arguments, and p1 has two parts:</p>
  
  <pre><code>    jason@jason-HP-43299:~/Programs/MachineLearning/SectionOne$ python TheanoPS00.py
      Array:   p1
      Type:   &lt;type 'numpy.ndarray'&gt;
      Shape:   (100, 2)
      Length:   100
      Data:   [[-0.0617  0.0534]
       [ 0.0299  0.0913]
       [ 0.0094  0.157 ]
       [ 0.1057  0.1535]
       [ 0.1412  0.2741]
       [ 0.0851  0.1426]
  </code></pre>
  
  <p>What exactly is happening here?</p>