terms.formula
Construct a terms Object from a Formula
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
.
- Keywords
- models
Usage
"terms"(x, specials = NULL, abb = NULL, data = NULL, neg.out = TRUE, keep.order = FALSE, simplify = FALSE, ..., allowDotAsName = FALSE)
Arguments
- x
- a formula.
- specials
- which functions in the formula should be marked as
special in the
terms
object? A character vector orNULL
. - abb
- Not implemented 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
- Not implemented in R.
- 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, followed by the interactions, all second-order, all third-order and so on. Effects of a given order are kept in the order specified. - simplify
- should the formula be expanded and simplified, the pre-1.7.0 behaviour?
- ...
- further arguments passed to or from other methods.
- allowDotAsName
- normally
.
in a formula refers to the remaining variables contained indata
. Exceptionally,.
can be treated as a name for non-standard uses of formulae.
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
object is returned. The object itself is
the re-ordered (unless keep.order = TRUE
) formula. In all
cases variables within an interaction term in the formula are
re-ordered by the ordering of the "variables"
attribute, which
is the order in which the variables occur in the formula.
See Also
Community examples
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