R/lavaan.R

In tzimiskes/causality: Examine The Causal Structure of Data

#' Turn a causality graph into a lavaan formula
#'
#' Use this function to convert a causality.graph into a lavaan formula so you
#' can fit the model to the data and assess the quality of the model from the
#' graph.
#' @param cgraph A causality.graph to be turned into a lavaan formula
#' @details currently, only DAGs are supported, though patterns and PDAGs with
#'   DAG extensions are accepted. Future work will inlcude PAGs, and including
#'   output from the FnFC family as a latent measurement model.
#' @return a \code{lavaan} formula, or an error
#' @examples
#' # turn the dag from Sachs(2009) DAG into a lavaan compatable formula
#' library(lavaan)
#' lavaan.forumula <- as.lavaan.formula(sachs.dag)
#' fit <- cfa(lavaan.formula, data = sachs.df)
#' @export
as.lavaan.formula <- function(cgraph)
{
    if (!is.cgraph(cgraph)) {
        stop("input must be a causality graph.")
    }
    if (!is.dag(cgraph))
        cgraph <- as.dag(cgraph)
    parents <- parents(cgraph)
    formulas <- c()
    for (node in names(parents)) {
        formulas <- c(formulas, paste(node, "~",
            paste(parents[[node]], collapse = " + ")))
    }
    return(paste(formulas, collapse = " ; "))
}