title: l_ply: how to pass the list's name attribute into the function?
body: <p>Say I have an R list like this:</p>
  
  <pre><code>&gt; summary(data.list)
                                   Length Class      Mode
  aug9104AP                        18     data.frame list
  Aug17-10_acon_7pt_dil_series_01  18     data.frame list
  Aug17-10_Picro_7pt_dil_series_01 18     data.frame list
  Aug17-10_PTZ_7pt_dil_series_01   18     data.frame list
  Aug17-10_Verat_7pt_dil_series_01 18     data.frame list
  </code></pre>
  
  <p>I want to process each data.frame in the list using <code>l_ply</code>, but I also need the name (e.g. aug9104AP) to be passed into the processing function along with the data.frame.  Something like:</p>
  
  <pre><code>l_ply(data.list,function(df,...) {
  
      cli.name&lt;- arg_to_access_current_list_item_name
  
      #make plots with df, use cli.name in plot titles
      #save results in a file called cli.name
  
    }, arg_to_access_current_list_item_name
  )
  </code></pre>
  
  <p>What should <code>arg_to_access_current_list_item_name</code> be?</p>