simDAG (version 0.3.0)

matrix2dag: Obtain a DAG object from a Adjacency Matrix and a List of Node Types

Description

The sim_from_dag function requires the user to specify the causal relationships inside a DAG object containing node information. This function creates such an object using a adjacency matrix and a list of node types. The resulting DAG will be only partially specified, which may be useful for the dag_from_data function.

Usage

matrix2dag(mat, type)

Value

Returns a partially specified DAG object.

Arguments

mat

A p x p adjacency matrix where p is the number of variables. The matrix should be filled with zeros. Only places where the variable specified by the row has a direct causal effect on the variable specified by the column should be 1. Both the columns and the rows should be named with the corresponding variable names.

type

A named list with one entry for each variable in mat, specifying the type of the corresponding node. See node for available node types.

Author

Robin Denz

Details

An adjacency matrix is simply a square matrix in which each node has one column and one row associated with it. For example, if the node A has a causal effect on node B, the matrix will contain 1 in the spot matrix["A", "B"]. This function uses this kind of matrix and additional information about the node type to create a DAG object. The resulting DAG cannot be used in the sim_from_dag function directly, because it will not contain the necessary parameters such as beta-coefficients or intercepts etc. It may, however, be passed directly to the dag_from_data function. This is pretty much it's only valid use-case. If the goal is to to specify a full DAG manually, the user should use the empty_dag function in conjunction with node calls instead, as described in the respective documentation pages and the vignettes.

The output will never contain time-dependent nodes. If this is necessary, the user needs to manually define the DAG.

See Also

empty_dag, node, node_td, dag_from_data

Examples

library(simDAG)

# simple example adjacency matrix
mat <- matrix(c(0, 0, 1, 0, 0, 1, 0, 0, 0), ncol=3, byrow=TRUE)
colnames(mat) <- c("age", "sex", "death")
rownames(mat) <- c("age", "sex", "death")

type <- list(age="rnorm", sex="rbernoulli", death="binomial")

matrix2dag(mat=mat, type=type)