model.matrix.coxph {survival}R Documentation

Model.matrix method for coxph models

Description

Reconstruct the model matrix for a cox model.

Usage

## S3 method for class 'coxph'
model.matrix(object, data, contrast.arg =
 object$contrasts, mf, ...)

Arguments

object the result of a coxph model
data optional, a data frame from which to obtain the data
contrast.arg optional, a contrasts object describing how factors should be coded
mf an optional model frame. Used interally when programs have already obtained a model frame.
... other possible argument to model.frame

Details

When there is a data argument this function differs from most of the other model.matrix methods in that the response variable for the original formual is not required to be in the data.

Value

The model matrix for the fit

Author(s)

Terry Therneau

See Also

model.matrix

Examples

fit1 <- coxph(Surv(time, status) ~ age + factor(ph.ecog), data=lung)
xfit <- model.matrix(fit1)

fit2 <- coxph(Surv(time, status) ~ age + factor(ph.ecog), data=lung,
                                 x=TRUE)
all.equal(model.matrix(fit1), fit2$x)

[Package survival version 2.36-2 Index]