title: Read first column as header in matrix for unsquare matrix
body: <p>I am trying to read in an adjacency matrix to create a network in graph
  I can read the data in with this:</p>
  
  <pre><code>Matrix_One &lt;- read.csv("Network Matrix.csv", header=TRUE)
  Matrix &lt;- as.matrix(Matrix_One)
  first_network &lt;- graph.adjacency(Matrix, mode= "directed", weighted=NULL)
  </code></pre>
  
  <p>But this doesn't acknowledge the first column are headers as I'm getting this warning message:</p>
  
  <blockquote>
    <p>Error in graph.adjacency.dense(adjmatrix, mode = mode, weighted = weighted,  : 
      At structure_generators.c:273 : Non-square matrix, Non-square matrix</p>
  </blockquote>
  
  <p>Any idea how to get R to read column1 as headers? </p>