# 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 3.3.3, License: Part of R 3.3.3*

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