title: Plot labels for specific geom_node_text
body: <p>I am trying to plot a network graph and show only the labels for the geom_node_text that have a centrality score above a specific threshold. My code is below: </p>
  
  <pre><code>rt_tbl %&gt;% 
  mutate(centrality = centrality_authority()) %&gt;% 
  ggraph(layout = 'kk') + 
  geom_edge_link(aes(), colour = "gray", alpha = 0.5) + 
  geom_node_point(aes(size = centrality, colour = centrality)) + 
  geom_node_text(data=subset(centrality &gt; 0.6), aes(centrality, label=name)) + 
  theme_graph(base_family = "Roboto Condensed", base_size = 13)
  </code></pre>
  
  <p>I encounter the following error:</p>
  
  <pre><code>Error in subset(centrality &gt; 100) : object 'centrality' not found
  </code></pre>
  
  <p>My data looks like this:</p>
  
  <pre><code># A tbl_graph: 1589 nodes and 3992 edges
  # A directed multigraph with 3 components
  # Node Data: 1,589 x 3 (active)
          name degree centrality
          &lt;chr&gt;  &lt;dbl&gt;      &lt;dbl&gt;
  1   Ashinlay1970     35 0.90053429
  2     WinTunMin1     25 0.66408597
  3 Yaminayeyaohn1      2 0.06080755
  4  TUNOO00655880      3 0.07609831
  5     inewagency      8 0.21569006
  6         KSwe03      4 0.12416238
  # ... with 1,583 more rows
  
  # Edge Data: 3,992 x 2
  from    to
  &lt;int&gt; &lt;int&gt;
  1     1    48
  2     1    49
  3     1     1
  # ... with 3,989 more rows
  </code></pre>