stats (version 3.3)

.checkMFClasses: Functions to Check the Type of Variables passed to Model Frames

Description

.checkMFClasses checks if the variables used in a predict method agree in type with those used for fitting.

.MFclass categorizes variables for this purpose.

Usage

.checkMFClasses(cl, m, ordNotOK = FALSE)
.MFclass(x)
.getXlevels(Terms, m)

Arguments

cl

a character vector of class descriptions to match.

m

a model frame.

x

any Robject.

ordNotOK

logical: are ordered factors different?

Terms

a terms object.

Value

• .MFclass returns a character string, one of "logical", "ordered", "factor", "numeric", "nmatrix.*" (a numeric matrix with a number of columns appended) or "other".

  .getXlevels returns a named character vector, or NULL.

Details

For applications involving model.matrix such as linear models we do not need to differentiate between ordered factors and factors as although these affect the coding, the coding used in the fit is already recorded and imposed during prediction. However, other applications may treat ordered factors differently: rpart does, for example.