formula.pdBlocked {nlme} | R Documentation

## Extract pdBlocked Formula

### Description

The `formula` attributes of the `pdMat` elements of `x` are extracted and returned as a list, in case `asList=TRUE`, or converted to a single one-sided formula when `asList=FALSE`. If the `pdMat` elements do not have a `formula` attribute, a `NULL` value is returned.

### Usage

    ## S3 method for class 'pdBlocked':
    formula(x, asList, ...)

### Arguments

`x` | an object inheriting from class `pdBlocked`, representing a positive definite block diagonal matrix.
`asList` | an optional logical value. If `TRUE`, a list with the formulas for the individual block diagonal elements of `x` is returned; else, if `FALSE`, a one-sided formula combining all individual formulas is returned. Defaults to `FALSE`.
`...` | some methods for this generic require additional arguments. None are used in this method.

### Value

a list of one-sided formulas, or a single one-sided formula, or `NULL`.

### Author(s)

Jose Pinheiro Jose.Pinheiro@pharma.novartis.com and Douglas Bates bates@stat.wisc.edu

### See Also

`pdBlocked`, `pdMat`

### Examples

    pd1 <- pdBlocked(list(~ age, ~ Sex - 1))
    formula(pd1)
    formula(pd1, asList = TRUE)

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