strg_prune() removes redundant relations from a stratigraphic graph by computing its transitive reduction. The result is a 'pruned' graph that follows Harris' "Law of Stratigraphical Succession": that only the uppermost and undermost relations are significant when placing a unit in a stratigraphic sequence.
Arguments
- strg
A
stratigraph()object to prune.
Value
A stratigraph with redundant relations removed.
Examples
bushy_stratigraphy <- stratigraph(
tibble::tibble(
id = letters[1:5],
above = list(NA, "a", "a", c("a", "b", "c"), c("a", "c", "d"))
),
"id", "above"
)
#> Warning: Invalid stratigraphic graph:
#> ! Contains redundant relations
#> ℹ Use `strg_prune()` to remove redundant relations
strg_prune(bushy_stratigraphy)
#> # A stratigraph: 5 units and 5 relations
#> # ✔ Valid stratigraphic graph
#> a
#> ┌─┴─┐
#> b c
#> └─┬─┘
#> d
#> │
#> e