# attrassign {survival}

### Description

The `"assign"`

attribute on model matrices describes which columns come from which terms in the model formula. It has two versions. R uses the original version, but the alternate version found in S-plus is sometimes useful.

### Usage

## S3 method for class 'default': attrassign((object, tt,...)) ## S3 method for class 'lm': attrassign((object,...))

### Arguments

- object
- model matrix or linear model object
- tt
- terms object
- ...
- ignored

### Details

For instance consider the following

survreg(Surv(time, status) ~ age + sex + factor(ph.ecog), lung)

R gives the compact for for assign, a vector (0, 1, 2, 3, 3, 3); which can be read as “the first column of the X matrix (intercept) goes with none of the terms, the second column of X goes with term 1 of the model equation, the third column of X with term 2, and columns 4-6 with term 3”. The alternate (S-Plus default) form is a list

$(Intercept) 1 $age 2 $sex 3 $factor(ph.ecog) 4 5 6

### Values

A list with names corresponding to the term names and elements that are vectors indicating which columns come from which terms

### See Also

### Examples

formula <- Surv(time,status)~factor(ph.ecog) tt <- terms(formula) mf <- model.frame(tt,data=lung) mm <- model.matrix(tt,mf) ## a few rows of data mm[1:3,] ## old-style assign attribute attr(mm,"assign") ## alternate style assign attribute attrassign(mm,tt)

Documentation reproduced from package survival, version 2.39-4. License: LGPL (>= 2)