Provides a symbolic description of a fitting model. Tells the model to do a linear transformation of the input values. The `predictors_index` parameter informs the positions of fields corresponding to formula independent variables. If no value is given, that all fields will be used as predictors.
sits_formula_linear(predictors_index = -2:0)
Index of the valid columns whose names are used to compose formula (default: -2:0).
A function that computes a valid formula.