Checks whether one vector of relations is the inverse of another. Typically used to confirm that "above" and "below" columns match and will result in the same stratigraphic graph.

## Arguments

- units
Vector of unit labels.

- relation1
First vector of relations.

- relation2
Second vector of relations.

## Examples

```
data("harris12")
strat_is_mirror(harris12$context, harris12$above, harris12$below)
#> [1] TRUE
```