title: Sorting rows and columns of adjacency matrix to reveal cliques
body: <p>I'm looking for a reordering technique to group connected components of an adjacency matrix together. </p>
  
  <p>For example, I've made an illustration with two groups, blue and green. Initially the '1's entries are distributed across the rows and columns of the matrix. By reordering the rows and columns, all '1''s can be located in two contiguous sections of the matrix, revealing the blue and green components more clearly.  </p>
  
  <p><img src="https://i.stack.imgur.com/f7vi4.png" alt="Illustration"></p>
  
  <p>I can't remember what this reordering technique is called. I've searched for many combinations of adjacency matrix, clique, sorting, and reordering. </p>
  
  <p>The closest hits I've found are</p>
  
  <ol>
  <li><p><a href="http://www.mathworks.com/help/matlab/ref/symrcm.html" rel="nofollow noreferrer"><code>symrcm</code></a> moves the elements closer to the diagonal, but does not make groups. </p></li>
  <li><p><a href="https://stackoverflow.com/questions/23657232/is-there-a-way-to-reorder-the-rows-and-columns-of-matrix-to-create-a-dense-corne">Is there a way to reorder the rows and columns of matrix to create a dense corner, in R?</a> which focuses on removing completely empty rows and columns</p></li>
  </ol>
  
  <p>Please either provide the common name for this technique so that I can google more effectively, or point me in the direction of a Matlab function. </p>