title: Why object becomes different after save/load to/from RData?
body: <p>I have a large <a href="http://rss.acs.unt.edu/Rdoc/library/Biobase/html/class.ExpressionSet.html" rel="nofollow">ExpressionSet</a> object (<a href="http://bioconductor.org" rel="nofollow">Bioconductor</a>) named <code>eset</code>. Can you explain why this happens? Why the object's copy is not identical to the original one after save/load?</p>
  
  <pre><code>&gt; e2=eset
  &gt; identical(e2,eset)
  [1] TRUE
  &gt; save(e2,file="test.RData")
  &gt; rm(e2)
  &gt; e2 # just to check the removal
  Error: object 'e2' not found
  &gt; load("test.RData")
  &gt; identical(e2,eset)
  [1] FALSE
  </code></pre>
  
  <p>Are there other ways to check the identity of two objects?</p>
  
  <p>If needed I'm working with R 2.15.1 under Windows 7.</p>