title: Dataframe[-list,] two commas meaning
body: <pre><code>unwanted &lt;- which((Tdata$V1 == "someString"))
  
  if(length(unwanted)&gt;0){
    Tdata &lt;- Tdata[-unwanted,]   
  }
  </code></pre>
  
  <p>I do not get this part <strong>Tdata[-unwanted,]</strong>. What does the dash mean? Whats the significance of leaving the second entry after the comma empty?</p>
  
  <p>I would appreciate any references to tutorials or any answer to my question.</p>