EssGraph-class {pcalg}

Class "EssGraph"

Description

This class represents an (observentional or interventional) essential graph.

Details

An observational or interventional Markov equivalence class of DAGs can be uniquely represented by a partially directed graph, the essential graph. Its edges have the following interpretation:

1. a directed edge a \longrightarrow b stands for an arrow that has the same orientation in all representatives of the Markov equivalence class;

2. an undirected edge a - b stands for an arrow that is oriented in one way in some representatives of the equivalence class and in the other way in other representatives of the equivalence class.

Extends

All reference classes extend and inherit methods from "envRefClass".

Constructor

new("EssGraph", nodes, in.edges, ...)

nodes

Vector of node names; cf. also field .nodes.

in.edges

A list of length p consisting of index vectors indicating the edges pointing into the nodes of the DAG.

Fields

.nodes:

Vector of node names; defaults to as.character(1:p), where p denotes the number of nodes (variables) of the model.

.in.edges:

A list of length p consisting of index vectors indicating the edges pointing into the nodes of the DAG.

targets

List of mutually exclusive intervention targets with respect to which Markov equivalence is defined.

score:

Object of class Score; used internally for score-based causal inference.

Class-Based Methods

Most class-based methods are only for internal use. Methods of interest for the user are:

repr():

Yields a representative causal model of the equivalence class, an object of a class derived from Score. Since the representative is not only characterized by the DAG, but also by appropriate parameters, the field score must be assigned for this method to work. The DAG is drawn at random; note that all representatives are statistically indistinguishable under a given set of intervention targets.

node.count():

Yields the number of nodes of the essential graph.

edge.count():

Yields the number of edges of the essential graph. Note that unoriented edges count as 2, whereas oriented edges count as 1 due to the internal representation.

Methods

plot

signature(x = "EssGraph", y = "ANY"): plots the essential graph. In the plot, undirected and bidirected edges are equivalent.

Author(s)

Alain Hauser ([e-mail])

See Also

ParDAG

Examples

showClass("EssGraph")