title: Ignore missing data frames when using rbind.fill on a list of data frames
body: <p>I have many data frames which are usually in the format <code>file.[i]</code>, but occasionally there are missing data frames:</p>
  
  <pre><code>file.1 file.2 file.3 file.4 file.5 file.6 file.7 file.9 file.11 file.13
  </code></pre>
  
  <p>What I tried to do is this:</p>
  
  <pre><code> dt &lt;- do.call(rbind.fill, 
                lapply(paste("file.", 1:length(filenames), sep=""), get))
  </code></pre>
  
  <p>And I get: </p>
  
  <pre><code>Error in FUN(c("file.1", "file.2", "file.3", "file.4", "file.5", "file.6",  : 
    object 'file.8' not found
  </code></pre>
  
  <p>Is there a way to make <code>rbind.fill</code> ignore the missing data frames?</p>