title: Filtering a large sparse matrix in python
body: <p>I have a large (60,000 x 60,000) symmetric document similarity matrix stored in the scipy sparse csr_matrix format.</p>
  
  <p>I want to find the indices of all values that are above a certain value. In other words, all the document pairs that have a similarity score greater than a certain value.</p>
  
  <p>When I try something like</p>
  
  <pre><code>matrix &gt; 0.9
  </code></pre>
  
  <p>my ipython kernel crashes. </p>
  
  <p>I'm new to scipy and numpy, so any help would be greatly appreciated.</p>