link: Extract link and inverse link functions from models

In gavinsimpson/gratia: Graceful 'ggplot'-Based Graphics and Other Functions for GAMs Fitted Using 'mgcv'

Extract link and inverse link functions from models

Description

Returns the link or its inverse from an estimated model, and provides a simple way to extract these functions from complex models with multiple links, such as location scale models.

Usage

link(object, ...)

## S3 method for class 'family'
link(object, parameter = NULL, which_eta = NULL, ...)

## S3 method for class 'gam'
link(object, parameter = NULL, which_eta = NULL, ...)

## S3 method for class 'bam'
link(object, parameter = NULL, which_eta = NULL, ...)

## S3 method for class 'gamm'
link(object, ...)

## S3 method for class 'glm'
link(object, ...)

## S3 method for class 'list'
link(object, ...)

inv_link(object, ...)

## S3 method for class 'family'
inv_link(object, parameter = NULL, which_eta = NULL, ...)

## S3 method for class 'gam'
inv_link(object, parameter = NULL, which_eta = NULL, ...)

## S3 method for class 'bam'
inv_link(object, parameter = NULL, which_eta = NULL, ...)

## S3 method for class 'gamm'
inv_link(object, ...)

## S3 method for class 'list'
inv_link(object, ...)

## S3 method for class 'glm'
inv_link(object, ...)

extract_link(family, ...)

## S3 method for class 'family'
extract_link(family, inverse = FALSE, ...)

## S3 method for class 'general.family'
extract_link(family, parameter, inverse = FALSE, which_eta = NULL, ...)

Arguments

object	a family object or a fitted model from which to extract the family object. Models fitted by stats::glm(), mgcv::gam(), mgcv::bam(), mgcv::gamm(), and gamm4::gamm4() are currently supported.
...	arguments passed to other methods.
parameter	character; which parameter of the distribution. Usually "location" but "scale" and "shape" may be provided for location scale models. Other options include "mu" as a synonym for "location", "sigma" for the scale parameter in mgcv::gaulss(), "pi" for the zero-inflation term in mgcv::ziplss(), "power" for the mgcv::twlss() power parameter, "xi", the shape parameter for mgcv::gevlss(), "epsilon" or "skewness" for the skewness and "delta" or "kurtosis" for the kurtosis parameter for mgcv::shash(), or "phi" for the scale parameter of mgcv::gammals() & mgcv::twlss().
which_eta	numeric; the linear predictor to extract for families mgcv::mvn() and mgcv::multinom().
family	a family object, the result of a call to family().
inverse	logical; return the inverse of the link function?

Author(s)

Gavin L. Simpson

Examples

load_mgcv()

link(gaussian())
link(nb())

inv_link(nb())

dat <- data_sim("eg1", seed = 4234)
mod <- gam(list(y ~ s(x0) + s(x1) + s(x2) + s(x3), ~1),
  data = dat,
  family = gaulss
)

link(mod, parameter = "scale")
inv_link(mod, parameter = "scale")

## Works with `family` objects too
link(shash(), parameter = "skewness")

gavinsimpson/gratia documentation built on May 4, 2024, 8:13 a.m.