title: Combining first two columns and turn it into row names in R data.frame
body: <p>I have a data that looks like this:</p>
  
  <pre><code>&gt; read.table("http://dpaste.com/1491018/plain/",header=TRUE)
          Probes Gene.symbol Stim1 Stim2 Stim3 Stim4
  1   1415670_at        Copg 1.133 1.049 1.013 1.124
  2   1415671_at    Atp6v0d1 1.068 1.006 1.082 1.234
  3   1415672_at      Golga7 1.010 0.883 1.061 1.029
  4   1415673_at        Psph 0.943 0.799 0.982 1.064
  5 1415674_a_at     Trappc4 1.048 0.960 1.191 1.118
  6   1415675_at        Dpm2 1.053 1.104 1.053 1.057
  </code></pre>
  
  <p>What I want to do is to create a new data frame that combines first two column 
  and turn it into row names,</p>
  
  <pre><code>                     Stim1 Stim2 Stim3 Stim4
  1415670_at-Copg      1.133 1.049 1.013 1.124
  1415671_at-Atp6v0d1  1.068 1.006 1.082 1.234
  1415672_at-Golga7    1.010 0.883 1.061 1.029
  1415673_at-Psph      0.943 0.799 0.982 1.064
  1415674_a_at-Trappc4 1.048 0.960 1.191 1.118
  1415675_at-Dpm2      1.053 1.104 1.053 1.057
  </code></pre>
  
  <p>How can this be done?</p>