title: Reading edges from a file. I can't define a graph
body: <p>I am new in R. I am working with igraph library. I am new using such library.</p>
  
  <p>I have a problem:</p>
  
  <p>I have a list of edges in a text file. It has two columns. The first has initial node, the second has the ending node.</p>
  
  <p>I am reading the file with:</p>
  
  <pre><code>g1 &lt;-read.table ("g1.txt")
  </code></pre>
  
  <p>The reading is successfull. </p>
  
  <p>with <code>ls.str(g1)</code> i get:</p>
  
  <pre><code>V1 :  int [1:995] 0 0 0 0 0 0 0 0 0 0 ...
  V2 :  int [1:995] 2 3 4 5 6 7 8 9 10 11 ...
  </code></pre>
  
  <p>when i try to define the graph with the just loaded edges I get:</p>
  
  <pre><code>Error in graph(g1) : (list) object cannot be coerced to type 'double'
  </code></pre>
  
  <p>How i could to define the graph from file's edges avoiding the above error?</p>