interaction               package:base               R Documentation

Compute Factor Interactions

Description:

     `interaction' computes a factor which represents the interaction
     of the given factors.  The result of `interaction' is always
     unordered.

Usage:

     interaction(..., drop=FALSE)

Arguments:

     ...: The factors for which interaction is to be computed.

    drop: If `drop' is `TRUE', empty factor levels are dropped from the
          result. The default is to retain all factor levels.

Value:

     A factor which represents the interaction of the given factors.

See Also:

     `factor'.

Examples:

     a <- gl(2, 2, 8)
     b <- gl(2, 4, 8)
     interaction(a, b)

