model.extract {base}

R Documentation

Extract Components from a Model Frame

Description

Returns the response, offset, subset, weights or other special components of a model frame passed as optional arguments to model.frame.

Usage

model.extract(frame, component)
model.offset(x)
model.response(data, type = "any")
model.weights(x)

Arguments

frame, x, data	A model frame.
component	The name of a components to extract, such as "weights", "subset".
type	One of "any", "numeric", "double". Using the either of latter two coerces the result to have storage mode "double".

Details

model.offset and model.response are equivalent to model.frame(, "offset") and model.frame(, "response") respectively.

model.weights is slightly different from model.frame(, "weights") in not naming the vector it returns.

Value

The specified component of the model frame, usually a vector.

See Also

model.frame, offset

Examples

data(esoph)
a <- model.frame(cbind(ncases,ncontrols) ~ agegp+tobgp+alcgp, data=esoph)
model.extract(a, "response")
stopifnot(model.extract(a, "response") == model.response(a))

a <- model.frame(ncases/(ncases+ncontrols) ~ agegp+tobgp+alcgp,
                 data = esoph, weights = ncases+ncontrols)
model.response(a)
model.extract(a, "weights")

a <- model.frame(cbind(ncases,ncontrols) ~ agegp,
                 something = tobgp, data = esoph)
names(a)
stopifnot(model.extract(a, "something") == esoph$tobgp)

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