model.matrix.coxph {survival} | R Documentation |
Reconstruct the model matrix for a cox model.
## S3 method for class 'coxph' model.matrix(object, data, contrast.arg = object$contrasts, mf, ...)
object |
the result of a coxph model |
data |
optional, a data frame from which to obtain the data |
contrast.arg |
optional, a contrasts object describing how factors should be coded |
mf |
an optional model frame. Used interally when programs have already obtained a model frame. |
... |
other possible argument to model.frame |
When there is a data
argument this function differs from most
of the other model.matrix
methods in that the response variable
for the original formual is not required to be in the data.
The model matrix for the fit
Terry Therneau
fit1 <- coxph(Surv(time, status) ~ age + factor(ph.ecog), data=lung) xfit <- model.matrix(fit1) fit2 <- coxph(Surv(time, status) ~ age + factor(ph.ecog), data=lung, x=TRUE) all.equal(model.matrix(fit1), fit2$x)