Relevel {Epi}R Documentation

Reorder and combine levels of a factor

Description

The levels of a factor are re-ordered so that the levels specified by ref is first and the others are moved down. This is useful for contr.treatment contrasts which take the first level as the reference. Levels may also be combined.

Usage

Relevel(f, ref, first = TRUE, collapse="+" )

Arguments

f An unordered factor
ref The names or numbers of levels to be the first. If ref is a list, factor levels mentioned in each list element are combined. If the list is named the names are used as new factor levels.
first Should the levels mentioned in ref come before those not?
collapse String used when collapsing factor levels.

Value

An unordered factor.

Examples

ff <- factor( sample( letters[1:5], 100, replace=TRUE ) )
table( ff, Relevel( ff, list( AB=1:2, "Dee"=4, c(3,5) ) ) )
table( ff, rr=Relevel( ff, list( 5:4, Z=c("c","a") ), coll="-und-", first=FALSE ) )

[Package Epi version 1.0.12 Index]