Create a matrix whose rows contain all possible combinations of the U,D,I models that are allowed.

This is an internal (non-exported) function. This help page provides additional documentation mainly intended for developers and expert users.

udi_model_matrix(R)

Arguments

R

the number of conditions

Value

a matrix that is Nmodel by R with each row containing a vector of "U", "D" and "I" characters corresponding to a valide model. Constraint is that there is at least one "D" in each row