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attrassign {survival}

Create new-style "assign" attribute
Package: 
survival
Version: 
2.37-7

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

terms,model.matrix

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 2.37-7. License: LGPL (>= 2)