BDgraph with Simple Examples
Date: 2025-08-29

#
BDgraph with Simple Examples

#### Reza Mohammadi (https://orcid.org/0000-0001-9538-0648)

#### 2025-08-29

The `R` package BDgraph provides statistical tools for Bayesian structure learning for undirected graphical models with continuous, count, binary, and mixed data. The package is implemented the recent improvements in the Bayesian graphical models’ literature, including Mohammadi and Wit (2015), Mohammadi et al. (2023), Mohammadi et al. (2017), Dobra and Mohammadi (2018), Mohammadi et al. (2023), and Vinciotti et al. (2024). Besides, the package contains several functions for simulation and visualization, as well as several multivariate datasets taken from the literature.

Install BDgraph using

    install.packages("BDgraph")

First, we load BDgraph package

    library(BDgraph)

Here are two simple examples to show how to use the functionality of the package.

# Example 1: Gaussian Graphical Models

Here is a simple example to see the performance of the package for the Gaussian graphical models. First, by using the function `bdgraph.sim()`, we simulate 200 observations (n = 200) from a multivariate Gaussian distribution with 15 variables (p = 15) and “scale-free” graph structure, as follows

    set.seed(20)

    data.sim = bdgraph.sim(n = 200, p = 15, graph = "scale-free", vis = TRUE)

Since the generated data are Gaussian, we run the `bdgraph()` function by choosing `method = "ggm"`, as follows

    bdgraph.obj = bdgraph(data = data.sim, method = "ggm", iter = 5000, verbose = FALSE)

To report confusion matrix with cutoff point 0.5:

    conf.mat(actual = data.sim, pred = bdgraph.obj, cutoff = 0.5)
                Actual
      Prediction  0  1
               0 91  4
               1  0 10

    conf.mat.plot(actual = data.sim, pred = bdgraph.obj, cutoff = 0.5)

To compare the result with the true graph

    compare(data.sim, bdgraph.obj, main = c("Target", "BDgraph"), vis = TRUE)

                     Target BDgraph
      True Positive      10  10.000
      True Negative      95  91.000
      False Positive      0   4.000
      False Negative      0   0.000
      F1-score            1   0.833
      Specificity         1   0.958
      Sensitivity         1   1.000
      MCC                 1   0.827

Now, as an alternative, we run the `bdgraph.mpl()` function which is based on the GGMs and marginal pseudo-likelihood, as follows

    bdgraph.mpl.obj = bdgraph.mpl(data = data.sim, method = "ggm", iter = 5000, verbose = FALSE)

    conf.mat(actual = data.sim, pred = bdgraph.mpl.obj)
                Actual
      Prediction  0  1
               0 91  4
               1  0 10
    conf.mat.plot(actual = data.sim, pred = bdgraph.mpl.obj)

We could compare the results of both algorithms with the true graph as follows

    compare(list(bdgraph.obj, bdgraph.mpl.obj), data.sim,
            main = c("Target", "BDgraph", "BDgraph.mpl"), vis = TRUE)

                     Target BDgraph BDgraph.mpl
      True Positive      14  10.000      10.000
      True Negative      91  91.000      91.000
      False Positive      0   0.000       0.000
      False Negative      0   4.000       4.000
      F1-score            1   0.833       0.833
      Specificity         1   1.000       1.000
      Sensitivity         1   0.714       0.714
      MCC                 1   0.827       0.827

To see the performance of the BDMCMC algorithm we could plot the ROC curve as follows

    plotroc(list(bdgraph.obj, bdgraph.mpl.obj), data.sim, cut = 200,
            labels = c("BDgraph", "BDgraph.mpl"), color = c("blue", "red"))

# Example 2: Gaussian Copula Graphical Models

Here is a simple example to see the performance of the package for the mixed data using Gaussian copula graphical models. First, by using the function `bdgraph.sim()`, we simulate 300 observations (n = 300) from mixed data (`type = "mixed"`) with 10 variables (p = 10) and “random” graph structure, as follows

    set.seed(2)

    data.sim = bdgraph.sim(n = 300, p = 10, type = "mixed", graph = "random", vis = TRUE)

Since the generated data are mixed data, we are using run the `bdgraph()` function by choosing `method = "gcgm"`, as follows:

    bdgraph.obj = bdgraph(data = data.sim, method = "gcgm", iter = 5000, verbose = FALSE)

To compare the result with the true graph, we could run

    compare(bdgraph.obj, data.sim, main = c("Target", "BDgraph"), vis = TRUE)

                     Target BDgraph
      True Positive      12   9.000
      True Negative      33  31.000
      False Positive      0   2.000
      False Negative      0   3.000
      F1-score            1   0.783
      Specificity         1   0.939
      Sensitivity         1   0.750
      MCC                 1   0.709

    plotroc(bdgraph.obj, data.sim, labels = "BDgraph", color = "blue")

For more examples see Mohammadi and Wit (2019).