my data set is similar to this and I want to use ifelse or other functions in R. I can do it easily in Excel, but not sure how to do it it in R.

```
df<-read.table(text=" Items Goods

Mug1    Cup1
Mug1    Mug2
Mug1    NA
Mug2    Mug1
Mug2    Cup2
Cup1    Mug1
Cup2    Mug2
Mug2    Cup1
Cup1    Mug2", header=TRUE)

```

Conditions are:

```
Mug1=Cup1
Mug2=Cup2
Cup1=Mug1
Cup2=Mug2

```

If I see the above condition, They are considered as correct. otherwise they are incorrect. I have searched, but I could not find any solution, but it is likely I have missed some websites. Any help 

I will get this table then

```
Items   Goods   Out
Mug1    Cup1    Correct
Mug1    Mug2    Incorrect
Mug1    NA  NA
Mug2    Mug1    Incorrect
Mug2    Cup2    Correct
Cup1    Mug1    Correct
Cup2    Mug2    Correct
Mug2    Cup1    Incorrect
Cup1    Mug2    Incorrect

```