title: R function-- the default value does not work?
body: <p>I am really new to R. Allow me to ask a beginner's question.</p>
  
  <p>When I type p.adjust, for example, I can see the following. It seems that the argument method is p.adjust.methods by default. I tried to trace the code but when I typed something like:</p>
  
  <pre><code>match.arg(p.adjust.methods)
  </code></pre>
  
  <p>It says: </p>
  
  <blockquote>
    <p>Error in match.arg(p.adjust.methods) : 'arg' must be of length 1</p>
  </blockquote>
  
  <p>Why?</p>
  
  <pre><code>&gt; p.adjust
  function (p, method = p.adjust.methods, n = length(p)) 
  {
      method &lt;- match.arg(method)
      ...
  }
  </code></pre>