title: Network error message Rstudio using igraph
body: <p>I am trying to make a network with these data points. I have them organized so the sources go to their proper target. However, I run into an error when I run,</p>
  <pre><code>library(igraph)
  
  
  links &lt;- data.frame(
    source=c(&quot;P&quot;,&quot;P&quot;,&quot;P&quot;,&quot;P&quot;,&quot;G&quot;,&quot;G&quot;,&quot;T&quot;,&quot;T&quot;,&quot;N&quot;,&quot;N&quot;,&quot;B&quot;,&quot;B&quot;,&quot;S&quot;,&quot;S&quot;,&quot;O&quot;,&quot;D&quot;),
    target=c(&quot;G&quot;,&quot;B&quot;,&quot;S&quot;,&quot;D&quot;,&quot;T&quot;,&quot;D&quot;,&quot;N&quot;,&quot;D&quot;,&quot;R&quot;,&quot;D&quot;,&quot;R&quot;,&quot;D&quot;,&quot;B&quot;,&quot;E&quot;,&quot;E&quot;,&quot;E&quot;),
    importance=(sample(1:4, 16, replace=T))
    )
  
  nodes &lt;- data.frame(
    name=LETTERS[1:10],
    carac=c( rep(&quot;bio&quot;,2),rep(&quot;affective&quot;,3),rep(&quot;cog&quot;,3),rep(&quot;neg&quot;,2))
    )
  
  
  network &lt;- graph_from_data_frame(d=links, vertices=nodes, directed=F) 
  
  </code></pre>
  <p>The error I get happens on the last line. It says</p>
  <p>Error in graph_from_data_frame(d = links, vertices = nodes, directed = F) : Some vertex names in edge list are not listed in vertex data frame</p>
  <p>I am not understanding what is wrong with my vertex data frame. I also do not know what the &quot;edge list&quot; is that it is referring to. Any help debugging would be appreciated!</p>
  <p>This is base code from r-graph-gallery that I am plugging my data into. It is supposed to create a network with links and nodes. I don't understand what replace or importance refers to, and it isn't explained on the website. This is what the base data looks like.</p>
  <pre><code>    library(igraph)
   
  links &lt;- data.frame(
      source=c(&quot;A&quot;,&quot;A&quot;, &quot;A&quot;, &quot;A&quot;, &quot;A&quot;,&quot;J&quot;, &quot;B&quot;, &quot;B&quot;, &quot;C&quot;, &quot;C&quot;, &quot;D&quot;,&quot;I&quot;),
      target=c(&quot;B&quot;,&quot;B&quot;, &quot;C&quot;, &quot;D&quot;, &quot;J&quot;,&quot;A&quot;,&quot;E&quot;, &quot;F&quot;, &quot;G&quot;, &quot;H&quot;, &quot;I&quot;,&quot;I&quot;),
      importance=(sample(1:4, 12, replace=T))
      )
  nodes &lt;- data.frame(
      name=LETTERS[1:10],
      carac=c( rep(&quot;young&quot;,3),rep(&quot;adult&quot;,2), rep(&quot;old&quot;,5))
      )
   
  network &lt;- graph_from_data_frame(d=links, vertices=nodes, directed=F)
  </code></pre>