title: Order the data by nth column, get rowname of first row, do this for each column
body: <p>Using this dataframe</p>
  
  <pre><code>head(pcaFM_clim_var_cos2[,1:5])
  
                       Dim.1      Dim.2     Dim.3        Dim.4      Dim.5
  dtr_mean_value_1 0.2583860 0.04524243 0.3004670 4.714854e-02 0.05262342
  dtr_mean_value_2 0.2470183 0.04818929 0.3380621 4.220726e-02 0.05577386
  dtr_mean_value_3 0.2459333 0.07231365 0.3690537 9.016624e-03 0.08165524
  dtr_mean_value_4 0.2740264 0.09818961 0.3053862 2.670571e-03 0.08860495
  dtr_mean_value_5 0.1910882 0.18521379 0.3373460 7.113687e-06 0.07396737
  dtr_mean_value_6 0.2109406 0.18532406 0.3185838 6.542807e-03 0.10550687
  </code></pre>
  
  <p>My intention is to:</p>
  
  <ol>
  <li>Order the data by Dim.1 </li>
  <li>Take the rowname of first row and append it to an empty vector </li>
  <li>Repeat this for Dim.2:Dim5 appending the first rowname  to the same vector.</li>
  </ol>
  
  <p>I tried this:</p>
  
  <pre><code>a &lt;- character()
  for (i in 1:5){
  pcaFM_clim_var_cos2[order(-pcaFM_clim_var_cos2[,i])]
    clim_var &lt;- append(a,head(pcaFM_clim_var_cos2[,0],1))
    }
  </code></pre>
  
  <p>But the vector (clim_var) is empty.</p>