Creates a candidate list of mixture variables.
gen.mixture(levels,vars)
An integer greater than 1. The number of levels of the mixture variables.
Either the number of variables, or a character vector of variable names.
Bob Wheeler bwheelerg@gmail.com
Please cite this program as follows:
Wheeler, R.E. (2004). gen.mixture. AlgDesign. The R project for statistical computing https://www.r-project.org/
Similar in function to gen.factorial(), but for mixture variables such that the rows sum to unity.
For levels=2, the identity matrix is produced, so that each variable is either 0 or 1. For
levels=3, rows are added to the identity containing two variables at 1/2 and the others at 0. etc.
In general, a mixture model of degree d will have the same number of terms as the candidate
list generated by gen.mixture for levels=d+1, and this will be optimal.