From therne@u @end|ng |rom m@yo@edu  Fri Apr  5 04:48:49 2019
From: therne@u @end|ng |rom m@yo@edu (Therneau, Terry M., Ph.D.)
Date: Thu, 04 Apr 2019 22:48:49 -0400
Subject: [Rd] subscripting a terms object
Message-ID: <b23057$bek7ei@ironport10.mayo.edu>

Someone sent me a bug report for survival2.44.1-1 that involves a model with both cluster 
and offset.? It turns out to be a 3 part issue with [.terms and my own untangle.specials 
routine.?? I've spent an evening sorting out the details.


 ? 1. The delete.response() function doesn't remove the response from the dataClasses 
attribute, which leads to a later failure in [.terms for no-response models.? Is there a 
reason for this, or can I make my patch include this oversight as well?

 ?2. [.terms messes up predvars and dataClasses if the model has an offset term in it.? 
(In select cases 1 and 2 can cancel out and give the correct dataClasses attribute.)

 ?3. The survival::untangle.specials routine assumed that you can use the same 
subscripting for the terms of a model and the term() object itself, which turns out to be 
almost always true, but only almost.

 ? The failure turns out to have probably been there since the Splus days, which tells one 
just how often such a model is used. (One of two edge case bugs sent to me in the first 
days after I pushed it to CRAN: a new release seems to attact them.)?? I'm willing to put 
together a patch, but given the rarity of these would folks prefer to wait until after the 
April release??? I'm fine with that.? I need the answer to 1 though.

Terry T.


	[[alternative HTML version deleted]]



[Rd] subscripting a terms object
Therneau, Terry M., Ph.D.