survival (version 2.36-5)

model.matrix.coxph: 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

Value

• The model matrix for the fit

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.

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)