contr.Power: A contrast function based on regular factorials
for number of levels a prime or prime power
Description
A contrast function based on regular factorials
for number of levels a prime or prime power
Usage
contr.Power(n, s = 2, contrasts = TRUE)
Value
contr.Power yields a matrix of contrasts. It can be used in
function model.matrix or anywhere where factors with the number of
levels a power of $s$ are used with contrasts. The exponent for s
is determined from the number of levels.
Arguments
n
integer or vector; either an integer number of levels of the factor for
which contrasts are created, which must be a a power of s; or a factor
whose number of levels is a power of s; or a vector of levels whose
number of elements is a power of s.
s
integer; prime or prime power
contrasts
logical; must be TRUE
Details
The function is a generalization (with slowest first instead of fastest first)
of function contr.FrF2 from package DoE.base. It is in this
package because it needs Galois field functionality from package lhs
for non-prime s. Its purpose is (was) the calculation of the
stratification (or space-filling) pattern by Tian and Xu (2022), see also
Groemping (2022). The package now calculates the pattern with function
contr.TianXu.