title: R - Change values of a dataframe column based on a second dataframe
body: <p>I need to change de names of the first column (ID_REF) of a dataframe based on the values of a second dataframe (column Gene_SYMBOL), matched by the first column of both dataframes (ID_REF and IlmnID).</p>
  
  <pre><code>df1
  ID_REF  Sample1 Sample2 Sample3
  cg00000292  0.2841738   1.212398    0.5326877
  cg00002426  -4.7278154  -4.217920   -4.1224573
  cg00003994  -5.7353341  -5.966922   -6.2235540
  
  df2
  IlmnID  NameIlmnStrand  AddressA_ID Gene_Symbol 
  cg00002426  cg00002426  TOP SLMAP
  cg00005847  cg00005847  BOT HOXD3
  cg00000292  cg00000292  TOP ATP2A1
  cg00006414  cg00006414  BOT ZNF398
  cg00003994  cg00003994  TOP MEOX2
  </code></pre>
  
  <p>my output:</p>
  
  <pre><code>new_df
      Gene_Symbol Sample1 Sample2 Sample3
      ATP2A1  0.2841738   1.212398    0.5326877
      SLMAP   -4.7278154  -4.217920   -4.1224573
      MEOX2   -5.7353341  -5.966922   -6.2235540
  </code></pre>