title: Confused on a very simple "==" test
body: <p>How is this possible?</p>
  
  <pre><code>&gt; a=TC_df$temp[561]
  &gt; a
  [1] 15.6
  &gt; a==15.6
  [1] FALSE
  &gt; a=="15.6"
  [1] TRUE
  &gt; class(a)
  [1] "numeric"
  </code></pre>