Extract pdBlocked Formula

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.

# 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

José Pinheiro and Douglas Bates bates@stat.wisc.edu

See also

pdBlocked, pdMat

Examples

pd1 <- pdBlocked(list(~ age, ~ Sex - 1))
formula(pd1)
#> [[1]]
#> ~age
#> <environment: 0x55c5463efb60>
#> 
#> [[2]]
#> ~Sex - 1
#> <environment: 0x55c5463efb60>
#> 
formula(pd1, asList = TRUE)
#> [[1]]
#> ~age
#> <environment: 0x55c5463efb60>
#> 
#> [[2]]
#> ~Sex - 1
#> <environment: 0x55c5463efb60>
#>