R/is.acyclic.R

In dagR: Directed Acyclic Graphs: Analysis and Data Simulation

is.acyclic <-
function(dag, maxSecs=NA)
{ #
  # Function to check by try() if a DAG appears cyclic.
  # using dag.ancestors, this only evaluates directed arcs;
  #
    acyclic <- rep(TRUE, length(dag$names))
    t0<-Sys.time();
    for (i in 1:length(dag$names)) {
        error <- try(dag.ancestors(dag, i), silent = TRUE)
        if (regexpr(pattern = "infinite recursion",
            text = error[1])[1] >= 0) {
            acyclic[i] <- FALSE
        }
        if (is.na(maxSecs)==FALSE)
        { if  (difftime(Sys.time(), t0, units="secs")>maxSecs)
          { return("evaluation aborted due to time limit");
          }
        }
    }
    if (length(acyclic[acyclic == FALSE]) == 0) {
        overall <- TRUE
    }
    else overall <- FALSE
    rv <- list(overall, acyclic)
    names(rv) <- c("acyclic", "nodewise")
    return(rv)
}