title: How to handle "argument 'incomparables != FALSE' is not used (yet)"?
body: <p>I want to check if a row in data.frame() is a duplicate of an existing row. As already pointed out <a href="https://stackoverflow.com/questions/5916854/existing-function-for-seeing-if-a-row-exists-in-a-data-frame">here</a> one way might to be to use the duplicate function. However, if I'm using the function I get the following error:</p>
  
  <pre><code>Error: argument 'incomparables != FALSE' is not used (yet)
  </code></pre>
  
  <p>In a quite old mail somebody pointed out that this is actually a bug in R (more information over <a href="https://stat.ethz.ch/pipermail/r-help/2009-March/193409.html" rel="nofollow noreferrer">here</a>). My data.frame() looks like this:</p>
  
  <pre><code>data.frame(val1=int,val2=int,val3=int,val4=float);
  </code></pre>
  
  <p>I'm wondering what the issue actually is since there seems to be no "NA" value in my data.frame, as</p>
  
  <pre><code>?duplicate
  </code></pre>
  
  <p>points out. This is maybe a very stupid question, but I'm quite new to R and would be glad for any tips regarding this issue!</p>
  
  <p>Thanks in advance,
   Michael</p>
  
  <p>P.S.: I've provided an example as suggested</p>
  
  <pre><code>table &lt;- NULL;
  
  foo &lt;- function(n, d, nh, v){
    newEntry &lt;- data.frame(node_i=n, node_j=nh, dst=d, phi=v);
  
    if(length(table != 0)){
      if(!duplicated(table, newEntry)){
        add(n, nh, d, v);
      }else{
        print("it is a duplicate!")    
      }
    }else{
      add(n, nh, d, v);
    }
  }
  
  add &lt;- function(n, d, nh, v){
    rbind(table, data.frame(node_i=n, node_j=nh, dst=d, phi=v)) -&gt;&gt; table;
  }
  
  bar &lt;- function(){
    foo(23,42,5,4.0);
    print(table);
    foo(22,42,5,4.0);  
    print(table);
    foo(23,42,5,4.0);
    print(table);
  }
  </code></pre>
  
  <p>However, this seems not to be a problem with duplicate() at all. I get the same error if I try to add another row <em>sigh</em>.</p>