title: Mean over multiple axis in NumPy
body: <p>I Want to write the code below as Pythonic way, applying mean over two axis. What the best way to do this?</p>
  <pre><code>import numpy as np
  
  m = np.random.rand(30, 10, 10)  
  m_mean = np.zeros((30, 1))    
  for j in range(30):
      m_mean[j, 0] = m[j, :, :].mean()
  </code></pre>