An object of class cross. See
read.cross for details.
mname1
The name of the first marker (as a character
string). (Alternatively, a vector with the two character strings, in
which case mname2 should not be given.)
mname2
The name of the second marker (as a character string).
eliminate.zeros
If TRUE, don't show the rows and columns that
have no data.
Value
A matrix containing the number of individuals having each possible
pair of genotypes. Genotypes for the first marker are in the rows;
genotypes for the second marker are in the columns.