I have a dataset here with 4 columns and 12 rows:
A       SIGMA.DAT                  WATER     nan
A       CUR.X.HEPTANE.dat          OIL       2.1373003
A       CUR.Y.HEPTANE.dat          OIL       2.1797340
B       SIGMA.DAT                  WATER     2.98415
B       CUR.X.HEPTANE.dat          OIL       4.2373003
B       CUR.Y.HEPTANE.dat          OIL       0.1497340
C       SIGMA.DAT                  WATER     7.98415
C       CUR.X.HEPTANE.dat          OIL       0.1373003
C       CUR.Y.HEPTANE.dat          OIL       3.1567340
D       SIGMA.DAT                  WATER     
D       CUR.X.HEPTANE.dat          OIL       0.1343003
D       CUR.Y.HEPTANE.dat          OIL       
I want to transform in into this dataframe:
          SIGMA.DAT            CUR.X.HEPTANE.dat      CUR.Y.HEPTANE.dat
A         nan                  2.1373003              2.179734
B         2.98415              4.2373003              0.1497340
C         7.98415              0.1373003              3.1567340
D         nan                  0.1343003              nan
Thanks for helping me out :)
 
    