Test node relationships

These functions test relationships between nodes in a DAG:

• is_parent() tests whether one node is a parent of another

• is_child() tests whether one node is a child of another

• is_ancestor() tests whether one node is an ancestor of another

• is_descendant() tests whether one node is a descendant of another

• is_adjacent() tests whether two nodes are adjacent (connected by an edge)

Usage

is_parent(.dag, .var, .node)

is_child(.dag, .var, .node)

is_ancestor(.dag, .var, .node)

is_descendant(.dag, .var, .node)

is_adjacent(.dag, .var, .node)

Arguments

.dag

A tidy_dagitty or dagitty object

.var

A character string specifying the variable to test

.node

A character string specifying the reference node

Value

A logical value indicating whether the relationship holds

Examples

dag <- dagify(
  y ~ x + z,
  x ~ z
)

is_parent(dag, "z", "x")
#> [1] TRUE
is_child(dag, "x", "z")
#> [1] TRUE
is_ancestor(dag, "z", "y")
#> [1] TRUE
is_descendant(dag, "y", "z")
#> [1] TRUE
is_adjacent(dag, "x", "y")
#> [1] TRUE