title: how to use ff package for reading and combining rds files to resolve memory issue?
body: <p>I have a list that contain several large files. All the files have the same column names. I want to combine them into an rds file and save with the filename in a column. I have read some of the SO answers and have written the following code. But I ham getting error. This is my attempt:</p>
  
  <pre><code>list.nam&lt;- list.files(pattern="*.I S")
  list.fil &lt;- lapply (list.nam, readRDS)
  #listfil is 3.8 GB
  # running this line gives error
  for (i in 1:length(list.fil)) 
  {list.fil[[i]]&lt;-cbind(list.fil[[i]],list.nam[i])
  } 
  data_rbind &lt;- do.call("rbind", list.fil)
  colnames(data_rbind)[c(1,2,3,4)]&lt;-c("Time","MRP", "Lot", "Name")
  saveRDS(data_rbind, "master.rds")
  </code></pre>
  
  <p>This is the error:</p>
  
  <pre><code>Error: cannot allocate vector of size 3.9 Mb
  In addition: There were 22 warnings (use warnings() to see them)   
  
  
  &gt; sessionInfo()
  R version 3.2.2 (2015-08-14)
  Platform: x86_64-w64-mingw32/x64 (64-bit)
  Running under: Windows 8 x64 (build 9200)
  
  locale:
  [1] LC_COLLATE=English_United States.1252  LC_CTYPE=English_United States.1252   
  [3] LC_MONETARY=English_United States.1252 LC_NUMERIC=C                          
  [5] LC_TIME=English_United States.1252    
  
  attached base packages:
  [1] stats     graphics  grDevices utils     datasets  methods   base     
  
  loaded via a namespace (and not attached):
  [1] tools_3.2.2
  </code></pre>
  
  <p>Please help.Is the problem I am facing is virtual address space limitation?</p>
  
  <p><strong>Is it possible to do the above operations on-disk using a package like ff? Any help is highly appreciated?</strong></p>