title: xtable header manipulation
body: <p>I am using xtable in R to get LaTeX code for tables. I want to modify the first element of the "header" (first row in LaTeX table) but I only saw an option to add text to the end of a line (using add.to.row in xtable). </p>
  
  <p>The following example should clarify what I want.</p>
  
  <p>Running</p>
  
  <pre><code>xtable(matrix(c(1,0.25,3,0.75),nrow=2,dimnames=list(c('absolute','relative'),c('GNU','Leo'))))
  </code></pre>
  
  <p>gives the output</p>
  
  <pre><code>% latex table generated in R 2.13.0 by xtable 1.5-6 package
  % Tue Jun 19 22:39:49 2012
  \begin{table}[ht]
  \begin{center}
  \begin{tabular}{rrr}
    \hline
   &amp; GNU &amp; Leo \\ 
    \hline
  absolute &amp; 1.00 &amp; 3.00 \\ 
    relative &amp; 0.25 &amp; 0.75 \\ 
     \hline
  \end{tabular}
  \end{center}
  \end{table}
  </code></pre>
  
  <p>I would like to get the line</p>
  
  <pre><code>  frequency &amp; GNU &amp; Leo \\ 
  </code></pre>
  
  <p>instead of the line</p>
  
  <pre><code>  &amp; GNU &amp; Leo \\
  </code></pre>
  
  <p>but I was unable to accomplish this using xtable. Let me know if you have an idea how to do this. Also, I apologize in advance if this is in the wrong place to ask or if I overlooked an answer or an obvious solution.</p>