model.framevlm: Construct the Model Frame of a VLM Object

Description

This function returns a data.frame with the variables. It is applied to an object which inherits from class "vlm" (e.g., a fitted model of class "vglm").

Usage

model.framevlm(object, setupsmart = TRUE, wrapupsmart = TRUE, ...)

Arguments

object

a model object from the VGAM Rpackage that inherits from a vector linear model (VLM), e.g., a model of class "vglm".

...

further arguments such as data, na.action, subset. See model.frame for more information on these.

setupsmart, wrapupsmart

Logical. Arguments to determine whether to use smart prediction.

Value

A data.frame containing the variables used in the object plus those specified in ....

Details

Since object is an object which inherits from class "vlm" (e.g., a fitted model of class "vglm"), the method will either returned the saved model frame used when fitting the model (if any, selected by argument model = TRUE) or pass the call used when fitting on to the default method.

This code implements smart prediction (see smartpred).

References

Chambers, J. M. (1992) Data for models. Chapter 3 of Statistical Models in S eds J. M. Chambers and T. J. Hastie, Wadsworth & Brooks/Cole.

Examples

Run this code

# Illustrates smart prediction
pneumo = transform(pneumo, let=log(exposure.time))
fit = vglm(cbind(normal,mild, severe) ~ poly(c(scale(let)), 2),
           fam=multinomial,
           data=pneumo, trace=TRUE, x=FALSE)
class(fit)

check1 = head(model.frame(fit))
check1
check2 = model.frame(fit, data=head(pneumo))
check2
all.equal(unlist(check1), unlist(check2)) # Should be TRUE

q0 = head(predict(fit))
q1 = head(predict(fit, newdata=pneumo))
q2 = predict(fit, newdata=head(pneumo))
all.equal(q0, q1)   # Should be TRUE
all.equal(q1, q2)   # Should be TRUE

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