title: matplotlib while loop (matplotlib.animation?)
body: <p>I am plotting data with matplotlib.  </p>
  
  <p>I would like to watch the data being plotted over a few seconds time. </p>
  
  <p>Current script (below) is close.. It closes the existing plot and makes a new plot including one additional data point for each while loop iteration. </p>
  
  <p>If the "fig=" and "ax1=" statements are instead typed above the loop, I get only a blank plot. </p>
  
  <pre><code>import numpy as np
  import matplotlib.pyplot as plt 
  import numpy as np
  import time
  #import matplotlib.animation as animation
  
  
  def animate2(i):
  
      k=1
  
      #fig=plt.figure()
      #ax1=fig.add_subplot(1, 1, 1)
  
      while k &lt;=len(i):
  
          fig=plt.figure()
          ax1=fig.add_subplot(1, 1, 1)
  
          ax1.clear
          ax1.plot(i[0:k, 0], i[0:k, 1])
  
          plt.show()
          time.sleep(1)
          k=k+1
  </code></pre>
  
  <p>Here the a sample np array I've used:</p>
  
  <pre><code>test_data=np.array([[3, 7],[1, 2],[8, 11],[5, -12],[20, 25], [-3, 30], [2,2], [17, 17]])
  
  animate2(test_data)
  </code></pre>
  
  <p>Also, if you think matplotlib.animation would work better, please provide an example!</p>