title: How can I group_by and summarize using a list of column names?
body: <p>Basically, I want to loop through, group the data by the columns in "list.group", and then create summary statistics for every column in "list.avg", "list.max", and "list.min" so that the columns are mpg_avg, wt_avg, hp_avg, mpg_max, hp_max... mpg_min, hp_min, etc.</p>
  
  <pre><code>data("mtcars")
      list.avg &lt;- list("mpg","wt","hp")
      list.max &lt;- list("mpg","hp","wt","qsec")
      list.min &lt;- list("mpg","hp","wt","qsec")
      list.group &lt;- list("cyl","vs","am","gear","carb")
  </code></pre>
  
  <p>So I should have a separate table for each column in list.group.</p>