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

Usage

model.extract(frame, component)
model.offset(frame)
model.response(frame)

Arguments

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")
all(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)
all(model.extract(a,"something")==esoph$tobgp) # TRUE