b.Init contains two sets (roc and rocnse) of
initial coefficients including mutation and selection parameters for
3 amino acids 'A', 'C', and 'D' in matrix format.
Both sets are in b format. ex.train contains a training set of 100 sequences including
3 reu13.df (codon counts in reu13 data frame format
divided by amino acids),
3 y (codon counts in simplified data frame format
divided by amino acids),
3 n (total amino acid counts in vector format
divided by amino acids), and
phi.Obs (observed phi values in vector format).
ex.test contains a testing set of the other 100 sequences in the
same format of ex.train.