R: Class "modelMatrix" and SubClasses

modelMatrix-class {MatrixModels} | R Documentation

## Class "modelMatrix" and SubClasses

### Description

The class `"modelMatrix"` and notably its subclass `"dsparseModelMatrix"` are used to encode additional information, analogously to what the standard R function `model.matrix()` returns.

### Objects from the Classes

Only `"dsparseModelMatrix"` and `"ddenseModelMatrix"` are “actual” (aka non-virtual) classes. For these, objects can be created by calls of the form `new("dsparseModelMatrix", x, assign, contrast)`, where `x` is a `dgCMatrix` classed object.

### Slots

The `"modelMatrix"` mother class contains `Matrix` plus two extra slots,

`assign`:

  `"integer"` vector of length `ncol(.)`, coding the variables which make up the matrix columns, see `model.matrix`.

`contrasts`:

  a named `list` of `contrasts`, as in `model.matrix()`.

`Dim`:

  integer vector of length two with the matrix dimensions.

`Dimnames`:

  list of length two, the `dimnames(.)` of the matrix.

whereas the (current only) actual classes `"d*ModelMatrix"`, have an at least an additional (`numeric` slot `"x"`. E.g., "dsparseModelMatrix" has the additional slots

`i`,`p`:

  row number and “pointer” integer vectors, see class `"dgCMatrix"`.

`x`:

  `"numeric"` vector of non-zero entries.

`factors`:

  a (possibly empty) `list` of factorizations.

### Extends

`"dsparseModelMatrix"` extends class `"dgCMatrix"` directly,
`"ddenseModelMatrix"` extends class `"dgeMatrix"` directly.

### Methods

show

  `signature(object = "modelMatrix")`: `show(.)` the matrix, but also the `assign` and `contrasts` slots.

print

  `signature(x = "modelMatrix")`: as `show()`, however (via `...`) allowing to pass further arguments for printing the matrix.

### Author(s)

Martin Maechler

### See Also

`sparse.model.matrix` will return a `"dsparseModelMatrix"` object. `model.Matrix` which is a simple wrapper around the traditional `model.matrix` and returns a `"ddenseModelMatrix"` object.

### Examples

    showClass("modelMatrix")
    showClass("dsparseModelMatrix")

    ## see   example(model.Matrix)

[Package MatrixModels version 0.4-1 Index]