title: How to subtract from columns and not rows in NumPy matrices?
body: <p>I have a matrix <code>X</code>:</p>
  
  <pre><code>[[  2.  nan  nan  nan]
   [  3.   2.  nan  nan]
   [ nan   5.   5.  nan]
   [ nan  nan  nan  nan]]
  </code></pre>
  
  <p>And a list <code>b</code>:</p>
  
  <pre><code>[-1.0, 2.0, 0.5, -2.0]
  </code></pre>
  
  <p>When I do <code>X - b</code> I get: </p>
  
  <pre><code>[[ 3.   nan  nan  nan]
   [ 4.   0.   nan  nan]
   [ nan  3.   4.5  nan]
   [ nan  nan  nan  nan]]
  </code></pre>
  
  <p>What if I wanted to subtract <code>b</code> across columns and not rows. </p>
  
  <p>I'm looking for something like <code>X - b.transpose()</code>:</p>
  
  <pre><code>[[ 3.   nan  nan  nan]
   [ 1.   0.   nan  nan]
   [ nan  4.5  4.5  nan]
   [ nan  nan  nan  nan]]
  </code></pre>