from collections import OrderedDict
from scipy.optimize import (
    Bounds
)


def get_gbt_regressor_model_contraints():
    """ return gbt regressor model contraints """
    constraints = OrderedDict()
    constraints['learning_rate'] = Bounds(lb=1e-6, ub=0.1)
    constraints['n_estimators'] = Bounds(lb=5, ub=200)
    constraints['subsample'] = Bounds(lb=0.3, ub=1.0)
    constraints['min_samples_split'] = Bounds(lb=2, up=100)
    constraints['min_samples_leaf'] = Bounds(lb=1, up=100)
    constraints['min_weight_fraction_leaf'] = Bounds(lb=1, ub=100)
    constraints['max_depth'] = Bounds(lb=1, ub=5)
    constraints['min_impurity_decrease'] = Bounds(lb=0.0, ub=3)
    constraints['alpha'] = Bounds(lb=0.0, ub=1.0)
    constraints['max_leaf_nodes'] = Bounds(lb=2, ub=10e3)
    constraints['tol'] = Bounds(lb=1e-6, ub=1)

    return constraints