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Query Collider Nodes

Source: R/query_functions.R
query_colliders.Rd

Identify all collider nodes in a DAG. A collider is a node that two or more edges point into. Bidirected edges count toward that total, so a node with one directed parent and one bidirected partner is a collider.

Usage

query_colliders(.tdy_dag)

Arguments

.tdy_dag

A tidy_dagitty or dagitty object

Value

A tibble with columns:

  • node: The collider node

  • parent_set: String representation of the directed parents

  • parents: List column containing the directed parents. A bidirected partner contributes an arrowhead but is not a parent, so a collider formed by bidirected edges can have fewer than two parents here.

  • is_activated: Logical indicating if the collider is conditioned on

Examples

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

query_colliders(dag)
#> # A tibble: 1 × 4
#>   node  parent_set parents   is_activated
#>   <chr> <chr>      <list>    <lgl>       
#> 1 z     {x, y}     <chr [2]> FALSE