title: Remove mean from numpy matrix
body: <p>I have a numpy matrix <code>A</code> where the data is organised column-vector-vise i.e <code>A[:,0]</code> is the first data vector, <code>A[:,1]</code> is the second and so on. I wanted to know whether there was a more elegant way to zero out the mean from this data. I am currently doing it via a <code>for</code> loop:</p>
  
  <pre><code>mean=A.mean(axis=1)
  for k in range(A.shape[1]):
      A[:,k]=A[:,k]-mean
  </code></pre>
  
  <p>So does numpy provide a function to do this? Or can it be done more efficiently another way?</p>