# 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

```
# S3 method for formula
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 or`NULL`

.- 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 in`data`

. 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

*Documentation reproduced from package stats, version 3.6.1, License: Part of R 3.6.1*