title: In numpy.sum() there is parameter called "keepdims". What does it do?
body: <p>In <code>numpy.sum()</code> there is parameter called <code>keepdims</code>. What does it do?</p>
  
  <p>As you can see here in the documentation:
  <a href="http://docs.scipy.org/doc/numpy/reference/generated/numpy.sum.html" rel="noreferrer">http://docs.scipy.org/doc/numpy/reference/generated/numpy.sum.html</a></p>
  
  <pre><code>numpy.sum(a, axis=None, dtype=None, out=None, keepdims=False)[source]
  Sum of array elements over a given axis.
  
  Parameters: 
  ...
  keepdims : bool, optional
      If this is set to True, the axes which are reduced are left in the result as
      dimensions with size one. With this option, the result will broadcast
      correctly against the input array.
  ...
  </code></pre>