title: Working with a list of lists of dataframes with different dimensions
body: <p>I am working with a list of lists of dataframes, like so:</p>
  
  <pre><code>results &lt;- list()
  for( i in 1:4 ) {
    runData &lt;- data.frame(id=i, t=1:10, value=runif(10))
    runResult &lt;- data.frame( id=i, avgValue=mean(runData$value))  
    results &lt;- c(results,list(list(runResult,runData)))
  }
  </code></pre>
  
  <p><em>The reason the data looks this way is its essentially how my actual data is generated from running simulations via clusterApply using the new parallel package in R 2.14.0, where each simulation returns a list of some summary results (runResult) and the raw data (runData)</em></p>
  
  <p>I would like to combine the first dataframe of the second level lists together (they are the same structure), and likewise the second dataframe of the second level lists. This <a href="https://stackoverflow.com/questions/1652522/rbind-dataframes-in-a-list-of-lists">question</a> seemed to be the answer, however all the dataframes have the same structure.</p>
  
  <p>The best method I've found so far is using <code>unlist</code> to make it a list of dataframes, where odd indices and even indices represent dataframes that need to be combined:</p>
  
  <pre><code>results &lt;- unlist(results,recursive=FALSE)
  allRunResults &lt;- do.call("rbind", results[seq(1,length(results),2)])
  allRunData &lt;- do.call("rbind", results[seq(2,length(results),2)])
  </code></pre>
  
  <p>I'm certain there's a better way to do this, I just don't see it yet. Can anyone supply one?</p>