title: How to keep a header when symmetrizing an adjacency matrix?
body: <p>I am using <code>symmetrize</code> function (<strong>sna</strong> package) to symmetrize an adjacency matrix that has row and column names. For example:<br>
  <a href="http://i.stack.imgur.com/v4tWl.png" rel="nofollow">sample matrix</a></p>
  
  <p>I used the following command to import matrix in R:</p>
  
  <pre><code>y &lt;- read.table("y.csv", header=T,row.names=1,na.strings="99", sep=",")
  </code></pre>
  
  <p>and then this command to symmetrize data:  </p>
  
  <pre><code>y_s &lt;-symmetrize(y,rule="strong", return.as.edgelist=FALSE)
  </code></pre>
  
  <p>After I run this command, the symmetrized matrix <code>y_s</code> no longer has row and column names. Is there any way I can modify this code so that row and column names are kept unchanged? Or, perhaps, there is a different way to symmetrize adjacency matrices? 
  Thank you. </p>