title: Displaying big numbers in xtable properly
body: <p>I know it might seem as a trivial question but I tried really hard to find solution and it was impossible.
  Assume I have a data frame like this where one column contatins big numbers:</p>
  
  <pre><code>Id    Value
  1     2158456456456.78
  2     123354554.24
  3     72323211215.77
  </code></pre>
  
  <p>I want to put that data frame into latex document using function xtable but I don't want the table to display the numbers like above but in a formatted way like this:</p>
  
  <pre><code>Id                   Value
  1     2 158 456 456 456.78
  2           123 354 554.24
  3        72 323 211 215.77
  </code></pre>
  
  <p>Any ideas?</p>