title: Formatting igraph pie vertex values from dataframe
body: <p>For a network analysis using igraph, I'm trying to set up my vertex metadata so that there are numeric vectors available for making pie graph vertices based off different combinations of columns from my dataframe.</p>
  <p>Using this example to illustrate the setup of my data:</p>
  <pre><code>df &lt;- data.frame(vName=c('Joe','Rose','Matt','Val'), Red=c(2.5, 1, 1, 0.9), Blue=c(3, 3, 1, 1), Yellow=c(2.9, 2.1, 3.2, 1.1))
  df
  #   vName Red Blue Yellow
  # 1   Joe 2.5    3    2.9
  # 2  Rose 1.0    3    2.1
  # 3  Matt 1.0    1    3.2
  # 4   Val 0.9    1    1.1
  </code></pre>
  <p>What's the best approach to assembling vectors as columns for each row by combining the data from specific columns? Ex. Where a new column RedBlue would return vector values as such:</p>
  <pre><code>df
  #   vName Red Blue Yellow   RedBlue
  # 1   Joe 2.5    3    2.9  2.5, 3.0
  # 2  Rose 1.0    3    2.1  1.0, 3.0
  # 3  Matt 1.0    1    3.2  1.0, 1.0
  # 4   Val 0.9    1    1.1  0.9, 1.0
  
  df$RedBlue
  #[[1]]
  #[1] 2.5 3.0
  
  #[[2]]
  #[2] 1.0 3.0
  
  #[[3]]
  #[3] 1.0 1.0
  
  #[[4]]
  #[4] 0.9 1.0
  </code></pre>
  <p>Or is there another approach that makes more sense in the context of building pie graph vertices in igraph using the vertex metadata?</p>
  <p>Much Thanks!</p>