model.extract {stats} | R Documentation |
Returns the response, offset, subset, weights or other
special components of a model frame passed as optional arguments to
model.frame
.
model.extract(frame, component) model.offset(x) model.response(data, type = "any") model.weights(x)
frame, x, data |
A model frame. |
component |
literal character string or name. The name of a
component 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" . |
model.extract
is provided for compatibility with S, which does
not have the more specific functions. It is also useful to extract
e.g. the etastart
and mustart
components of a
glm
fit.
model.offset
and model.response
are equivalent to
model.extract(, "offset")
and model.extract(, "response")
respectively.
model.weights
is slightly different from
model.frame(, "weights")
in not naming the vector it returns.
The specified component of the model frame, usually a vector.
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)