title: Set Column Names to Indices in a Dataframe
body: <p>I have a dataframe d with 2901 rows.</p>
  
  <pre><code>head(d)
  index           V1           V2           V3           V4           V5           V6
  1     1 0.0061810090 0.0064328712 0.0061484017 0.0061779441 0.0065441666 0.0059717158
  2     2 0.0006206956 0.0006461670 0.0006193262 0.0006194541 0.0006557183 0.0006260470
  3     3 0.0009515612 0.0009837086 0.0009368350 0.0009451564 0.0010080150 0.0009061030
  4     4 0.0018297131 0.0019052822 0.0017963541 0.0018318636 0.0019390136 0.0017270329
  5     5 0.0004890663 0.0005188195 0.0004888804 0.0004982749 0.0005183072 0.0004724337
  6     6 0.0024545661 0.0025594465 0.0024123898 0.0024603748 0.0026013768 0.0023221302
  </code></pre>
  
  <p>For function and plot conveniency I had to transpose it.</p>
  
  <pre><code>td &lt;- t(d)
  </code></pre>
  
  <p>Showing the last newly created 6 columns:</p>
  
  <pre><code>       [,2896]      [,2897]      [,2898]      [,2899]      [,2900]      [,2901]
  index 2.896000e+03 2.897000e+03 2.898000e+03 2.899000e+03 2.900000e+03 2.901000e+03
  V1    6.588442e-04 5.831684e-04 1.121615e-03 2.809617e-04 3.073592e-04 5.295372e-04
  V2    6.900545e-04 6.069315e-04 1.171652e-03 2.924802e-04 3.166947e-04 5.650248e-04
  </code></pre>
  
  <p>How can I set the new column names as proper indices? </p>