Constructs a formula for mgcv::gam() by wrapping numeric predictors with sufficient unique values in s() terms and keeping factors as linear terms.
build_gam_formula(target, features, data, min_unique = 4L, default_k = 10L)A formula object suitable for mgcv::gam()
Character: target variable name
Character vector: predictor variable names
Data frame used to check variable types and unique value counts
Integer: minimum number of unique values for a numeric predictor to be wrapped in s(). Default 4 (mgcv needs at least k=3 knots).