terms.formula              package:base              R Documentation

A function to construct a terms object from a formula.

Description:

     This function takes a formula and some optional arguments and
     constructs a terms object. The terms object can then be used to
     construct a `model.matrix'.

Usage:

     terms.formula(x, specials=NULL, abb=NULL, data=NULL, neg.out=TRUE,
                   keep.order=FALSE, ...)

Arguments:

       x: A formula.

specials: What functions in the formula should be marked as special in
          the terms object.

     abb: Unused in R.

    data: A data frame from which the meaning of the special symbol `.'
          can be inferred. It is unused if there is no `.' in the
          formula.

 neg.out: `TRUE' if terms with a minus, `-' should be removed. If FALSE
          these are kept in and indicate a negative order (for
          fractionate?).

keep.order: A logical value indicating whether the terms should keep
          their positions. If FALSE the terms are reordered so that
          main effects come first.

     ...: further arguments passed to or from other methods.

Details:

     Not all of the options work in the same way that they do in S and
     not all are implemented.

Value:

     A `terms' object is returned.

See Also:

     `terms.object',  `terms.default'

