title: No visible binding for global variable Note in R CMD check
body: <p>I noticed in checking a package that I obtain notes "no visible binding for global variable" when I use functions like <code>subset</code> that use verbatim names of list elements as arguments.</p>
  
  <p>For example with a data frame:</p>
  
  <blockquote>
    <p>foo &lt;- data.frame(a=c(TRUE,FALSE,TRUE),b=1:3)</p>
  </blockquote>
  
  <p>I can do silly things like:</p>
  
  <pre><code>subset(foo,a)
  transform(foo,a=b)
  </code></pre>
  
  <p>Which work as expected. The R code check in R CMD however doesn't understand that these refer to elements and complains about there not being any visible bindings of global variables. </p>
  
  <p>While this works ok, I don't really like having notes in my package and prefer for it to pass the check with no errors, warnings and notes at all. I also don't really want to rework my code too much. Is there a way to write these codes so that it is clear the arguments do not refer to global variables?</p>