utility_formula {spdesign} | R Documentation |
Create formulas from the utility functions such that we can create correct model matrices.
utility_formula(x)
x |
An object of class utility |
Note that this function should be used on a cleaned utility expression and
**not** an updated utility expression. This is because we are converting
dummy coded attributes to factors prior to calling model.matrix
.
This ensures that dummy coded attributes are correctly returned with the
model matrix.
A list of formula expressions for the utility functions