R: Equality of Two or More Factors

Diag {gnm} | R Documentation

## Equality of Two or More Factors

### Description

Converts two or more factors into a new factor whose value is 0 where the original factors are not all equal, and nonzero otherwise.

### Usage

    Diag(..., binary = FALSE)

### Arguments

`...` | One or more factors
`binary` | Logical

### Details

Used mainly in regression models for data classified by two or more factors with the same levels. By default, operates on k-level factors to produce a new factor having k+1 levels; if `binary = TRUE` is specified, the result is a coarser binary variable equal to 1 where all of the input factors are equal and 0 otherwise.

If the original levels are identical the levels of the factor created in the `binary = FALSE` case will be in the same order, with `"."` added as the first level. Otherwise the levels of the new factor will be `"."` followed by the sorted combined levels.

### Value

Either a factor (if `binary = FALSE`) or a 0-1 numeric vector (if `binary = TRUE`).

### Author(s)

David Firth and Heather Turner

### See Also

`Symm`

### Examples

    rowfac <- gl(4, 4, 16)
    colfac <- gl(4, 1, 16)
    diag4by4 <- Diag(rowfac, colfac)
    matrix(Diag(rowfac, colfac, binary = TRUE), 4, 4)

[Package gnm version 1.1-2 Index]