title: Adjacency matrix in R
body: <p>I want to find the adjacency matrix from a csv file that includes the information as follows:</p>
  
  <pre><code>A B 
  1 2
  1 3
  1 4
  2 5
  3 7
  </code></pre>
  
  <p>and so on. There are 100 nodes but everytime I try to create a matrix and subsequently plot the graph, the error is that it is a non-square matrix.
  Can somebody help me with the correct code in R?</p>