R: Expand nested factors

expand.nested {coxme} | R Documentation

## Expand nested factors

### Description

Expand out the data frame for a nested factor such as (1| a/b). This is used by the variance function routines of `coxme`.

### Usage

    expand.nested(x)

### Arguments

`x` | A data frame containing the nesting variables

### Details

The initialize function of a `coxme` variance family is passed, as one of its arguments, a data frame `G` containing the grouping variables, each of which is a factor.. Assume a nested factor `(1| a/b)` in the model formula and a data set whose first few rows are:

        a    b
        1    1
        1    2
        2    1

The function will replace the second column with a variable named `a/b` and values of 1/1, 1/2, 2/1, etc.

### Value

an updated data frame

### Author(s)

Terry Therneau

### See Also

`coxme`, `coxmeMlist`

[Package coxme version 2.2-7 Index]