Works for all the fitters. In the multi-trait case the coefficients come named
"level|trait"; use trait= to slice out one trait.
Arguments
- fit
result of model(), model_mt(), model_ar1(), model_threshold(), model_survival() or snp_blup()
- group
covariance group; by default the group of the direct genetic term: the first pedigree or genomic term that is not
maternal()orindirect(), else the firstkernel()with an estimated variance over the animals (most of its levels are animals of the pedigree, or there is no pedigree term), else the firstmaternal()term, else the first otherkernel()with an estimated variance, else the first group; the same default inebv(),solutions(),accuracy(),h2()andh2_curve()- trait
multi-trait only: which trait to slice out; all of them if omitted