title: save data with unequal lengths without introducing NA's
body: <p>I have a question about saving a dataframe with unequal lengths. Is there way to save table with variable lengths without introducing NA's or something? Here is an example with NA's but that is not what i want to save.</p>
  
  <pre><code>x &lt;- list(matrix(c(1,4,3,2), ncol = 2,                   
  dimnames = list(c("A","B"), NULL)),            
  matrix(c(23,9,4,4,22,54), ncol = 2,                   
  dimnames = list(c("C","D","E"), NULL))) 
  
  out &lt;- lapply(x, rownames) 
  foo &lt;- function(x, max, repl = NA) {     
  if(length(x) == max)         
  out &lt;- x     
  else {         
  out &lt;- rep(repl, max)         
  out[seq_along(x)] &lt;- x     
  }     
  out 
  } 
  out &lt;- lapply(out, foo, max = max(sapply(out, length))) 
  (out &lt;- do.call(rbind, out))
  </code></pre>
  
  <p>Thank you</p>