I would like to subtract paired sample by each other to get the differences between `Cancer` and `Normal`. In my example I would subtract the numbers in `value` for which the two rows which `Pairing` are the same. I am not sure were to start. 

```
            value    Sample      Group  Pairing Dataset
Sample_100G 8.063495 Sample_100G Cancer     100 Wei et al.
Sample_100R 3.226365 Sample_100R Normal     100 Wei et al.
Sample_106G 4.551518 Sample_106G Cancer     106 Wei et al.
Sample_106R     0    Sample_106R Normal     106 Wei et al.
Sample_122G     0    Sample_122G Cancer     122 Wei et al.
Sample_122R 0.000000 Sample_122R Normal     122 Wei et al.

```

out

```
 Diff      Group  Pairing Dataaset
 8.06-3.22  Cancer     100 Wei et al.
 4.55-0     Cancer     106 Wei et al.
 0-0        Cancer     122 Wei et al.

```