title: How to prevent R from dropping leading zeros in an integer vector
body: <p>Is there any way of stopping R from dropping leading zeros in an integer? e.g.,</p>
  
  <p>a&lt;-c(00217,00007,00017) </p>
  
  <p>I understand this is not the correct way of writing integers. Sadly I've been given a text file (person and non-R code are not around anymore) containing thousands of vectors in a single list:
  list(drugA=c(...), drugB=c(....),........)</p>
  
  <p>I need to keep the leading zeros as 00002 becomes 2. I could load these thousands of values in and then write a function to parse the list and convert into characters whilst correcting for any number that isn't five characters long but I was hoping for a speedy alternative. </p>
  
  <p><strong>UPDATE1</strong>
  An example of the text file I've been provided:</p>
  
  <pre><code>list(CETUXIMAB=c(05142,05316),
  DORNASEALFA=c(94074),
  ETANERCEPT=c(05342,99075),
  BIVALIRUDIN=c(04400,09177),
  LEUPROLIDE=c(02074,03219,91035,91086),
  PEGINTERFERONALFA2A=c(03162),
  ALTEPLASE=c(00486,01032,03371,05314),
  DARBEPOETINALFA=c(02217,03421),
  GOSERELIN=c(99221),
  RETEPLASE=c(00157),
  ERYTHROPOIETIN=c(92078,92122)) 
  </code></pre>
  
  <p>I have truncated the list as there are thousands of vectors. This was a text file generated using a program written in C++ (code not available). Some of the values e.g., RETEPLASE=c(00157) becomes truncated to 157. </p>