I have two data frames. `df1` has some NAs in a column that I'm interested in, and `df2` has this same column but with the values I need. I want to fill those values in df1 according to the rownames (the rownames in df2 are found in df1).

For example, df1 would be something like this:

```
              Age    Gender     
Patient_1      NA     Male  # Has NA
Patient_3      30     Male
Patient_66     45     Female
Patient_10     NA     Female  # Has NA
Patient_11     67     Female
Patient_23     NA     Male  # Has NA

```

and df2 contains the same information but only for the samples that have **NA** in the age column in df1:

```
              Age    Gender
Patient_1     59      Male
Patient_10    80      Female
Patient_23    21      Male

```

Now how do I fill those Age values, from df2 to df1, for each sample?

I tried this:

```
for(i in 1:length(df1$Age)){

  if(rownames(df1)[i] == rownames(df2)[i]){

    df1$Age[[i]] = df2$Age[[i]]

  }
}

```

That didn't work as it filled only a subset of the values for some reason, some values are still NA in df1.