How to access cox.zph components

Question

I would like to use the P value of cox.zph in a Sweave document, something like this:

<<echo=FALSE,results=tex>>=
campo = campos[1]
m1=coxph(Surv(TimeVar,EventVar)~Factor)
z=cox.zph(m1)
….
@

If I assign to an object print(cox.zph(m1)):

temp = print(cox.zph(m1)) 

I have the p value in the third component temp[3], but the instruction print(z) outputs the results to the document, and I want only to store the P value in another variable, not to show the results.

I tried invisible function, but it doesn’t work for me.

Answer 1

To answer your specific question, use results=hide in your list of options.

<<echo=FALSE,results=hide>>=
campo = campos[1]
m1=coxph(Surv(TimeVar,EventVar)~Factor)
z=cox.zph(m1)
temp = print(x)
@

You can then access the temp variable. A better solution is to pull out the parts of the z object you need. So in your case, this would be:

##z is a list
z1 = z[[1]]

The variable z1 is a matrix that contains the information you need.