This class contains information on the formula passed in
a call to pim. The object is used to create the
model matrix of a pim (see model.matrix)
termsa terms.object derived from the formula
has.specialsa logical value indicating whether the right-hand
side of the original formula contains special functions like
L and R
has.lhs.funa logical value indicating whether the left-hand
side of the original formula contains special functions. These
exclude the functions P and PO but
include functions like Surv. See Details
predictorsa character vector with the names of all the variables mentioned in the right-hand side of the formula.
responsean character vector with the name of the response variable.
lhsa call with the processed left-hand side of the formula
origa formula object with the original formula
penvan environment object to which the
formula is related (i.e. the environment containing possible
L and R function definitions.) See Details.
has.intercepta logical value indicating whether the formula has an explicit intercept (indicated by + 1)
Although a future version of this package will include the
possibility to fit survival models, this is currently not implemented.
If the pim function encounters special functions on the
left-hand side (i.e. when has.lhs.fun is TRUE), the
model won't be calculated.
The slot penv contains a reference to an environment
In most cases, this will be the environment contained in a
pim.environment object. Note though that the
pim.formula object only contains a link to the environment.
The extra slots contained in the pim.environment object
are NOT copied to the pim.formula. Also keep
in mind that the environment linked to the pim.environment
object will continue to exist even after deleting the
pim.environment itself, and this for as long as the
pim.formula object exists.
This class is not exported and hence cannot be extended. It serves internal use in the pim package only.