I have two separate dataframes:

```
> head(data)

  Drug.Substance.Calcium Drug.Substance.Glycine Drug.Substance.Histidine
    1                             45.0                                120.0                                                              
    2                             43.0                                100.0                                                               
    3                             33.7                                 9.6                                                              

```

I want to add units to the column names. The units can be found in a different dataset (in the `UOM` column)

```
> head(ag_parameter_6[10:13,])
    X                PARAMETER DATA_TYPE PARAMETER_TYPE    UOM
10  9   Drug Substance.Calcium    double              D mmol/L
11 10 Drug Substance.Endotoxin    string              D       
12 11   Drug Substance.Glycine    double              D  mg/mL
13 12 Drug Substance.Histidine    double              D mmol/L

```

How can I modify the `data` dataframe so that each column has the correct units (found in UOM)?