title: plot multiple arrows between scatter points
body: <p>I'm trying to plot multiple arrows between two sets of scatter points. Plotting a line is easy enough with <code>ax.plot</code>. But I'm trying to implement an arrow instead of a line. The arrows don't appear to be aligning between the points.</p>
  <p>So if the line plot is initialised below, it works fine. But the quiver plot does not plot alone  the same lines.</p>
  <pre><code>import pandas as pd
  import matplotlib.pyplot as plt
  import numpy as np
  
  df = pd.DataFrame(np.random.randint(-50,50,size=(100, 4)), columns=list('ABCD'))
  
  fig, ax = plt.subplots()
  
  x1 = df['A']
  y1 = df['B']
  
  x2 = df['C']
  y2 = df['D']
  
  AB = plt.scatter(x1, y1, c = 'blue', marker = 'o', s = 10, zorder = 3)
  CD = plt.scatter(x2, y2, c = 'red', marker = 'o', s = 10, zorder = 2)
  
  # plot line between points
  #ax.plot([x1,x2],[y1,y2], color = 'black', linestyle = '--', linewidth = 0.5)
  
  ax.quiver([x1, x2], [y1, y2])
  </code></pre>