D-relationship between variables — Assess d-separation between variables • ggdag

D-separation is a key concept in causal structural models. Variables are d-separated if there are no open paths between them. The node_d*() functions label variables as d-connected or d-separated. The ggdag_d*() functions plot the results. The *_dconnected(), *_dseparated(), and *_drelationship() functions essentially produce the same output and are just different ways of thinking about the relationship. See dagitty::dseparated() for details.

Usage

node_dconnected(
  .tdy_dag,
  from = NULL,
  to = NULL,
  controlling_for = NULL,
  as_factor = TRUE,
  ...
)

node_dseparated(
  .tdy_dag,
  from = NULL,
  to = NULL,
  controlling_for = NULL,
  as_factor = TRUE
)

node_drelationship(
  .tdy_dag,
  from = NULL,
  to = NULL,
  controlling_for = NULL,
  as_factor = TRUE
)

ggdag_drelationship(
  .tdy_dag,
  from = NULL,
  to = NULL,
  controlling_for = NULL,
  ...,
  edge_type = "link_arc",
  size = 1,
  node_size = 16,
  text_size = 3.88,
  label_size = text_size,
  text_col = "white",
  label_col = "black",
  edge_width = 0.6,
  edge_cap = 10,
  arrow_length = 5,
  use_edges = TRUE,
  use_nodes = TRUE,
  use_stylized = FALSE,
  use_text = TRUE,
  use_labels = FALSE,
  label_geom = geom_dag_label_repel,
  unified_legend = TRUE,
  key_glyph = draw_key_dag_point,
  label = NULL,
  text = NULL,
  node = deprecated(),
  stylized = deprecated(),
  collider_lines = TRUE
)

ggdag_dseparated(
  .tdy_dag,
  from = NULL,
  to = NULL,
  controlling_for = NULL,
  ...,
  edge_type = "link_arc",
  size = 1,
  node_size = 16,
  text_size = 3.88,
  label_size = text_size,
  text_col = "white",
  label_col = "black",
  edge_width = 0.6,
  edge_cap = 10,
  arrow_length = 5,
  use_edges = TRUE,
  use_nodes = TRUE,
  use_stylized = FALSE,
  use_text = TRUE,
  use_labels = FALSE,
  label_geom = geom_dag_label_repel,
  unified_legend = TRUE,
  key_glyph = draw_key_dag_point,
  label = NULL,
  text = NULL,
  node = deprecated(),
  stylized = deprecated(),
  collider_lines = TRUE
)

ggdag_dconnected(
  .tdy_dag,
  from = NULL,
  to = NULL,
  controlling_for = NULL,
  ...,
  edge_type = "link_arc",
  size = 1,
  node_size = 16,
  text_size = 3.88,
  label_size = text_size,
  text_col = "white",
  label_col = "black",
  edge_width = 0.6,
  edge_cap = 10,
  arrow_length = 5,
  use_edges = TRUE,
  use_nodes = TRUE,
  use_stylized = FALSE,
  use_text = TRUE,
  use_labels = FALSE,
  label_geom = geom_dag_label_repel,
  unified_legend = TRUE,
  key_glyph = draw_key_dag_point,
  label = NULL,
  text = NULL,
  node = deprecated(),
  stylized = deprecated(),
  collider_lines = TRUE
)

Arguments

.tdy_dag: A tidy_dagitty or dagitty object
from: A character vector with starting node name(s), or NULL. If NULL, checks DAG for exposure variable.
to: A character vector with ending node name(s), or NULL. If NULL, checks DAG for outcome variable.
controlling_for: A set of variables to control for. This can be a character vector of variable names, a list of the form list(c(...)), or NULL. When NULL, no control is applied. Default is NULL.
as_factor: Logical. Should the column be a factor?
...: additional arguments passed to tidy_dagitty()
edge_type: The type of edge, one of "link_arc", "link", "arc", "diagonal".
size: A numeric value scaling the size of all elements in the DAG. This allows you to change the scale of the DAG without changing the proportions.
node_size: The size of the nodes.
text_size: The size of the text.
label_size: The size of the labels.
text_col: The color of the text.
label_col: The color of the labels.
edge_width: The width of the edges.
edge_cap: The size of edge caps (the distance between the arrowheads and the node borders).
arrow_length: The length of arrows on edges.
use_edges: A logical value. Include a geom_dag_edges*() function? If TRUE, which is determined by edge_type.
use_nodes: A logical value. Include geom_dag_point()?
use_stylized: A logical value. Include geom_dag_node()?
use_text: A logical value. Include geom_dag_text()?
use_labels: A logical value. Include a label geom? The specific geom used is controlled by label_geom.
label_geom: A geom function to use for drawing labels when use_labels = TRUE. Default is geom_dag_label_repel. Other options include geom_dag_label, geom_dag_text_repel, geom_dag_label_repel2, and geom_dag_text_repel2.
unified_legend: A logical value. When TRUE and both use_edges and use_nodes are TRUE, creates a unified legend entry showing both nodes and edges in a single key, and hides the separate edge legend. This creates cleaner, more compact legends. Default is TRUE.
key_glyph: A function to use for drawing the legend key glyph for nodes. If NULL (the default), the glyph is chosen automatically based on the unified_legend setting. When provided, this overrides the automatic selection. Common options include draw_key_dag_point, draw_key_dag_combined, and draw_key_dag_collider.
label: The bare name of a column to use for labels. If use_labels = TRUE, the default is to use label.
text: The bare name of a column to use for geom_dag_text(). If use_text = TRUE, the default is to use name.
node: Deprecated.
stylized: Deprecated.
collider_lines: Logical. Should paths opened by conditioning on colliders be shown?

Value

a tidy_dagitty with a d_relationship column for variable D relationship or a ggplot

Examples

library(ggplot2)
dag <- dagify(m ~ x + y)
dag |> ggdag_drelationship("x", "y")

dag |> ggdag_drelationship("x", "y", controlling_for = "m")


dag |>
  node_dseparated("x", "y") |>
  ggplot(aes(x = x, y = y, xend = xend, yend = yend, shape = adjusted,
             col = d_relationship)) +
  geom_dag_edges() +
  geom_dag_collider_edges() +
  geom_dag_node() +
  geom_dag_text(col = "white") +
  theme_dag() +
  scale_adjusted(include_color = FALSE)


dag |>
  node_dconnected("x", "y", controlling_for = "m") |>
  ggplot(aes(x = x, y = y, xend = xend, yend = yend, shape = adjusted,
             col = d_relationship)) +
  geom_dag_edges() +
  geom_dag_collider_edges() +
  geom_dag_node() +
  geom_dag_text(col = "white") +
  theme_dag() +
  scale_adjusted(include_color = FALSE)


dagify(m ~ x + y, m_jr ~ m) |>
  tidy_dagitty(layout = "nicely") |>
  node_dconnected("x", "y", controlling_for = "m_jr") |>
  ggplot(aes(x = x, y = y, xend = xend, yend = yend, shape = adjusted,
             col = d_relationship)) +
  geom_dag_edges() +
  geom_dag_collider_edges() +
  geom_dag_node() +
  geom_dag_text(col = "white") +
  theme_dag() +
  scale_adjusted(include_color = FALSE)