title: How to hide some dots in a matplotlib scatter?
body: <pre><code>import matplotlib.pyplot as plt
  import numpy as np
  y = np.random.rand(100)
  plt.scatter(list(range(100)), y)
  </code></pre>
  
  <p>The commend above will draw a scatter with matplotlib.</p>
  
  <p>Suppose I want to hide the points whose values are less than 0.5. At the same time, I should remain the x-axis unchanged. How should I do it?</p>