HMgmm-class {qpgraph} | R Documentation

## Homogeneous mixed graphical Markov model

### Description

The `"HMgmm"` class is the class of homogeneous mixed graphical Markov models defined within the `qpgraph` package to store simulate and manipulate this type of graphical Markov models (GMMs).

An homogeneous mixed GMM is a family of multivariate conditional Gaussian distributions on mixed discrete and continuous variables sharing a set of conditional independences encoded by means of a marked graph. Further details can be found in the book of Lauritzen (1996).

### Objects from the Class

Objects can be created by calls of the form `HMgmm(g, ...)` corresponding to constructor methods or `rHMgmm(n, g, ...)` corresponding to random simulation methods.

### Slots

`pI`:

  Object of class `"integer"` storing the number of discrete random variables.

`pY`:

  Object of class `"integer"` storing the number of continuous random variables.

`g`:

  Object of class `graphBAM-class` storing the associated marked graph.

`vtype`:

  Object of class `"factor"` storing the type (discrete or continuous) of each random variable.

`dLevels`:

  Object of class `"integer"` storing the number of levels of each discrete random variable.

`a`:

  Object of class `"numeric"` storing the vector of additive linear effects on continuous variables connected to discrete ones.

`rho`:

  Object of class `"numeric"` storing the value of the marginal correlation between two continuous random variables.

`sigma`:

  Object of class `dspMatrix-class` storing the covariance matrix.

`mean`:

  Object of class `"numeric"` storing the mean vector.

`eta2`:

  Object of class `"numeric"` storing for each continuous variable connected to a discrete one, the fraction of variance of the continuous variable explained by the discrete one.

### Methods

`HMgmm(g)`

  Constructor method where `g` can be either an adjacency matrix or a `graphBAM-class` object.

`rHMgmm(n, g)`

  Constructor simulation method that allows one to simulate homogeneous mixed GMMs where `n` is the number of GMMs to simulate and `g` can be either a markedGraphParam object, an adjacency matrix or a `graphBAM-class` object.

`names(x)`

  Accessor method to obtain the names of the elements in the object `x` that can be retrieved with the `$` accessor operator.

`$`

  Accessor operator to retrieve elements of the object in an analogous way to a `list`.

`dim(x)`

  Dimension of the homogeneous mixed GMM corresponding to the number of discrete and continuous random variables.

`dimnames(x)`

  Names of the discrete and continuous random variables in the homogeneous mixed GMM.

`show(object)`

  Method to display some bits of information about the input homogeneous mixed GMM specified in `object`.

`summary(object)`

  Method to display a sumamry of the main features of the input homogeneous mixed GMM specified in `object`.

`plot(x, ...)`

  Method to plot the undirected graph associated to the the input homogeneous mixed GMM specified in `x`. It uses the plotting capabilities from the `Rgraphviz` library to which further arguments specified in `...` are further passed.

### Author(s)

R. Castelo

### References

Lauritzen, S.L. Graphical models. Oxford University Press, 1996.

### See Also

UGgmm

[Package qpgraph version 2.21.2 Index]