title: R- function %in% - different result with the same argument
body: <p>I don't understand the code below :  </p>
  
  <pre><code>Huto19952013&lt;-seq(as.Date("1995/1/1"), as.Date("2013/12/31"), "days")
  &gt; Huto[1] %in% Huto19952013 
  [1] FALSE
  &gt; Huto[1]
  [1] "1995-01-01"
  &gt; "1995-01-01" %in% Huto19952013
  [1] TRUE
  </code></pre>
  
  <p>Why the result is different? </p>
  
  <p>Thanks for your help</p>