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