form=as.formula(object$call[[2]]) mat=model.matrix(form,newdata) coefi=coef(object,id=id) xvars=names(coefi) mat[,xvars]%*%coefi } regfit.best=regsubsets(Salary~.,data=Hitters,nvmax=19) coef(regfit.best,10) k=10 set.seed(1) folds=sample(1:k,nrow(Hitters),replace=TRUE) cv...