An S4 class to represent a stratigraphic matrix.

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).

`units`

A

`character`

vector giving the stratigraphic unit names.

When a matrix is first created, an identifier is generated (UUID v4). This ID is preserved when coercing to another class. Thus, the object ID is unique within the same class, but two objects of different classes can have the same ID. This makes it possible to identify objects representing the same initial data and associate them with the results of specific computations.

In the code snippets below, `x`

is a `*Matrix`

object.

`get_id(x)`

Get the ID of

`x`

.`get_dates(x)`

and`set_dates(x) <- value`

Get or set the dates of

`x`

.`get_coordinates(x)`

and`set_coordinates(x) <- value`

Get or set the geographical coordinates of

`x`

.

In the code snippets below, `x`

is a `*Matrix`

object.

`dim(x)`

Returns the dimension of

`x`

.`nrow(x)`

Returns the number of rows present in

`x`

.`ncol(x)`

Returns the number of columns present in

`x`

.`dimnames(x)`

,`dimnames(x) <- value`

Retrieves or sets the row dimnames of

`x`

according to`value`

.`rownames(x)`

,`rownames(x) <- value`

Retrieves or sets the row names of

`x`

according to`value`

.`colnames(x)`

,`colnames(x) <- value`

Retrieves or sets the column names of

`x`

according to`value`

.

In the code snippets below, `x`

is a `*Matrix`

object.

`x[i, j]`

Extracts elements selected by subscripts

`i`

and`j`

. Indices are`numeric`

,`integer`

or`character`

vectors or empty (missing) or`NULL`

. Numeric values are coerced to`integer`

as by`as.integer`

(and hence truncated towards zero). Character vectors will be matched to the name of the elements. An empty index (a comma separated blank) indicates that all entries in that dimension are selected. Returns an object of the same class as`x`

.`x[[i]]`

Extracts a single element selected by subscript

`i`

.

Other matrix:
`AbundanceMatrix-class`

,
`CountMatrix-class`

,
`IncidenceMatrix-class`

,
`LogicalMatrix-class`

,
`Matrix-class`

,
`NumericMatrix-class`

,
`OccurrenceMatrix-class`

,
`SimilarityMatrix-class`

,
`coerce()`

# Principles of Archaeological Stratigraphy, fig. 12 harris <- matrix( data = c(2, 1, 3, 1, 4, 1, 5, 2, 5, 3, 5, 4, 6, 5, 7, 1, 7, 6, 8, 1, 8, 6, 9, 7, 9, 8), ncol = 2, byrow = TRUE, dimnames = list(NULL, c("lower", "upper")) ) strati <- as_stratigraphy(harris) get_units(strati)#> [1] "1" "2" "3" "4" "5" "6" "7" "8" "9"