# model.matrix.coxph

From survival v3.1-8
by Terry Therneau

##### Model.matrix method for coxph models

Reconstruct the model matrix for a cox model.

- Keywords
- survival

##### Usage

```
# S3 method for coxph
model.matrix(object, data=NULL, contrast.arg =
object$contrasts, ...)
```

##### 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

- …
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 formula is *not* required to be in the data.

If the data frame contains a `terms`

attribute then it is
assumed to be the result of a call to `model.frame`

, otherwise
a call to `model.frame`

is applied with the data as an argument.

##### Value

The model matrix for the fit

##### See Also

##### Examples

```
# NOT RUN {
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)
# }
```

*Documentation reproduced from package survival, version 3.1-8, License: LGPL (>= 2)*

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