R: Construct the Model Frame of a VLM Object

model.framevlm {VGAM} | R Documentation

## 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 R package 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.

### 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`).

### Value

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

### 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.

### See Also

`model.frame`, `model.matrixvlm`, `predictvglm`, `smartpred`.

### Examples

    # Illustrates smart prediction
    pneumo <- transform(pneumo, let = log(exposure.time))
    fit <- vglm(cbind(normal,mild, severe) ~ poly(c(scale(let)), 2),
                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

[Package VGAM version 1.1-3 Index]