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An S4 class to represent a stratigraphic matrix.

Details

A stratigraphic matrix represents directed relationships between stratigraphic units. A stratigraphic matrix is an adjacency matrix (a non symmetric square matrix with zeros on its main diagonal), suitable to build a directed acyclic graph (DAG).

Note

This class inherits from AdjacencyMatrix.

Author

N. Frerebeau

Examples

## Principles of Archaeological Stratigraphy, fig. 12
## Build an adjacency list
harris <- data.frame(
  younger = c(1, 1, 1, 2, 3, 4, 5, 6, 6, 6, 7, 8, 1, 1),
  older = c(2, 3, 4, 5, 5, 5, 6, 7, 8, 9, 9, 9, 7, 8)
)

## Coerce to adjacency matrix
strati <- as_stratigraphy(harris, reduce = TRUE)

## Define interface layers
set_interface(strati) <- c("1" = FALSE, "2" = TRUE,  "3" = FALSE,
                           "4" = FALSE, "5" = FALSE, "6" = TRUE,
                           "7" = FALSE, "8" = FALSE, "9" = FALSE)

## Stratigraphic graph
graph <- as_graph(strati)
plot(graph)