Expand factors to a set of contrasts
Substitutes all factors in a data frame with the set of contrasts with which that factor is associated
expandFactors( data, ... )
- A data frame.
- Additional arguments to be passed to model.matrix
expandFactors function replaces all of the factors in a data frame with the set of contrasts output by the
contrasts function or
model.matrix. It may be useful for teaching purposes when explaining relationship between ANOVA and regression.
A data frame.
This package is under development, and has been released only due to teaching constraints. Until this notice disappears from the help files, you should assume that everything in the package is subject to change. Backwards compatibility is NOT guaranteed. Functions may be deleted in future versions and new syntax may be inconsistent with earlier versions. For the moment at least, this package should be treated with extreme caution.
grading <- data.frame( teacher = factor( c("Amy","Amy","Ben","Ben","Cat") ), gender = factor( c("male","female","female","male","male") ), grade = c(75,80,45,50,65) ) # expand factors using the default contrasts (usually treatment contrasts) expandFactors( grading ) # specify the contrasts using the contrasts.arg argument to model.matrix my.contrasts <- list( teacher = "contr.helmert", gender = "contr.treatment" ) expandFactors( grading, contrasts.arg = my.contrasts )