title: Create new dataframe conditional to the rows and columns of an existing dataframe
body: <p>I have a dataframe with the following structure:</p>
  
  <pre><code>Name   CIN   EBV    GS    MSI
  ab1    0.4   0.3   0.45   0.7
  cd2    0.25  0.1   0.3    0.4
  ...    ...   ...   ...    ...
  </code></pre>
  
  <p>From that existing dataframe, I would like to create a new one which has new rows with the values of column A vs each other column name and its respective value from that existing one. Since I can not express myself much better than that and I know that this explanation is a bit messed up, here goes a draft of the output dataframe that I would like to obtain:</p>
  
  <pre><code>Name    C_S    P 
  ab1     CIN   0.4
  ab1     EBV   0.3
  ab1     GS    0.45
  ab1     MSI   0.7
  cd2     CIN   0.25
  cd2     EBV   0.1
  cd2     GS    0.3
  cd2     MSI   0.4
  </code></pre>