title: How to customize a Graph using Matplotlib
body: <p>I need help to customize a graph using Matplotlib.<br />
  I want to draw a graph like this.<br />
  <a href="https://i.stack.imgur.com/IFwh5.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/IFwh5.png" alt="enter image description here" /></a></p>
  <p>My python code is:</p>
  <pre><code>import numpy as np
  import matplotlib as mpl
  import matplotlib.pyplot as plt
  
  data=np.loadtxt('input.txt', delimiter = ',')
  
  x = np.arange(0,64)
  y = np.arange(0,64)
  
  fig, ax = plt.subplots()
  im = ax.imshow(data)
  
  #customize colorbar
  cmap = mpl.colors.ListedColormap(['royalblue','blue','red'])    
  
  im = ax.contourf(y,x,data,cmap=cmap)
  fig.colorbar(im)
  
  plt.show()
  </code></pre>
  <p>and my output is:</p>
  <p><a href="https://i.stack.imgur.com/antdg.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/antdg.png" alt="enter image description here" /></a></p>
  <p>So what should i do ?<br />
  Thank you.</p>