terms.object {base} | R Documentation |
An object of class terms
holds information about a
model. Usually the model was specified in terms of a
formula
and that formula was used to determine the terms
object.
The object itself is simply the formula supplied to the call of
terms.formula
. The object has a number of attributes
and they are used to construct the model frame.
An object with the following attributes:
factors |
A matrix of variables by terms showing which variables appear in which terms. |
term.labels |
A character vector containing the labels for each of the terms in the model. |
variables |
A list of the variables in the model |
intercept |
Either 0, indicating no intercept is to be fit, or 1 indicating that an intercept is to be fit. |
order |
A vector of the same length as term.labels
indicating the order of interaction for each term |
response |
|
offset |
If the model contains offset terms there
is an offset attribute indicating which terms are offsets |
specials |
If the specials argument was given to
terms.formula there is a specials attribute, a
list of vectors indicating the terms that contain these special
functions. |
The object has class c("terms", "formula")
.
These objects are different from those found in S. In particular
there is no formula
attribute, instead the object is itself a
formula. Thus, the mode of a terms object is different as well.
An example of the specials
argument can be seen in the
aov
function.