# MIPLearn: Extensible Framework for Learning-Enhanced Mixed-Integer Optimization # Copyright (C) 2020, UChicago Argonne, LLC. All rights reserved. # Released under the modified BSD license. See COPYING.md for more details. from unittest.mock import Mock import pytest from numpy.testing import assert_array_equal from miplearn import GurobiPyomoSolver, LearningSolver, Regressor from miplearn.components.objective import ObjectiveValueComponent from miplearn.types import TrainingSample, Features from tests.fixtures.knapsack import get_knapsack_instance import numpy as np @pytest.fixture def features() -> Features: return { "Instance": { "User features": [1.0, 2.0], } } @pytest.fixture def sample() -> TrainingSample: return { "Lower bound": 1.0, "Upper bound": 2.0, "LP value": 3.0, } @pytest.fixture def sample_without_lp() -> TrainingSample: return { "Lower bound": 1.0, "Upper bound": 2.0, } @pytest.fixture def sample_without_ub() -> TrainingSample: return { "Lower bound": 1.0, "LP value": 3.0, } def test_sample_xy( features: Features, sample: TrainingSample, ) -> None: x_expected = { "Lower bound": [[1.0, 2.0, 3.0]], "Upper bound": [[1.0, 2.0, 3.0]], } y_expected = { "Lower bound": [[1.0]], "Upper bound": [[2.0]], } xy = ObjectiveValueComponent.sample_xy(features, sample) assert xy is not None x_actual, y_actual = xy assert x_actual == x_expected assert y_actual == y_expected def test_sample_xy_without_lp( features: Features, sample_without_lp: TrainingSample, ) -> None: x_expected = { "Lower bound": [[1.0, 2.0]], "Upper bound": [[1.0, 2.0]], } y_expected = { "Lower bound": [[1.0]], "Upper bound": [[2.0]], } xy = ObjectiveValueComponent.sample_xy(features, sample_without_lp) assert xy is not None x_actual, y_actual = xy assert x_actual == x_expected assert y_actual == y_expected def test_sample_xy_without_ub( features: Features, sample_without_ub: TrainingSample, ) -> None: x_expected = { "Lower bound": [[1.0, 2.0, 3.0]], "Upper bound": [[1.0, 2.0, 3.0]], } y_expected = {"Lower bound": [[1.0]]} xy = ObjectiveValueComponent.sample_xy(features, sample_without_ub) assert xy is not None x_actual, y_actual = xy assert x_actual == x_expected assert y_actual == y_expected def test_fit_xy() -> None: x = { "Lower bound": np.array([[0.0, 0.0], [1.0, 2.0]]), "Upper bound": np.array([[0.0, 0.0], [1.0, 2.0]]), } y = { "Lower bound": np.array([[100.0]]), "Upper bound": np.array([[200.0]]), } reg = Mock(spec=Regressor) reg.clone = Mock(side_effect=lambda: Mock(spec=Regressor)) comp = ObjectiveValueComponent(regressor=reg) assert comp.ub_regressor is None assert comp.lb_regressor is None comp.fit_xy(x, y) assert reg.clone.call_count == 2 assert comp.ub_regressor is not None assert comp.lb_regressor is not None assert comp.ub_regressor.fit.call_count == 1 assert comp.lb_regressor.fit.call_count == 1 assert_array_equal(comp.ub_regressor.fit.call_args[0][0], x["Upper bound"]) assert_array_equal(comp.lb_regressor.fit.call_args[0][0], x["Lower bound"]) assert_array_equal(comp.ub_regressor.fit.call_args[0][1], y["Upper bound"]) assert_array_equal(comp.lb_regressor.fit.call_args[0][1], y["Lower bound"]) def test_fit_xy_without_ub() -> None: x = { "Lower bound": np.array([[0.0, 0.0], [1.0, 2.0]]), "Upper bound": np.array([[0.0, 0.0], [1.0, 2.0]]), } y = { "Lower bound": np.array([[100.0]]), } reg = Mock(spec=Regressor) reg.clone = Mock(side_effect=lambda: Mock(spec=Regressor)) comp = ObjectiveValueComponent(regressor=reg) assert comp.ub_regressor is None assert comp.lb_regressor is None comp.fit_xy(x, y) assert reg.clone.call_count == 1 assert comp.ub_regressor is None assert comp.lb_regressor is not None assert comp.lb_regressor.fit.call_count == 1 assert_array_equal(comp.lb_regressor.fit.call_args[0][0], x["Lower bound"]) assert_array_equal(comp.lb_regressor.fit.call_args[0][1], y["Lower bound"]) def test_sample_predict( features: Features, sample: TrainingSample, ) -> None: x, y = ObjectiveValueComponent.sample_xy(features, sample) comp = ObjectiveValueComponent() comp.lb_regressor = Mock(spec=Regressor) comp.ub_regressor = Mock(spec=Regressor) comp.lb_regressor.predict = Mock(side_effect=lambda _: np.array([[50.0]])) comp.ub_regressor.predict = Mock(side_effect=lambda _: np.array([[60.0]])) pred = comp.sample_predict(features, sample) assert pred == { "Lower bound": 50.0, "Upper bound": 60.0, } assert_array_equal(comp.ub_regressor.predict.call_args[0][0], x["Upper bound"]) assert_array_equal(comp.lb_regressor.predict.call_args[0][0], x["Lower bound"]) def test_sample_predict_without_ub( features: Features, sample_without_ub: TrainingSample, ) -> None: x, y = ObjectiveValueComponent.sample_xy(features, sample_without_ub) comp = ObjectiveValueComponent() comp.lb_regressor = Mock(spec=Regressor) comp.lb_regressor.predict = Mock(side_effect=lambda _: np.array([[50.0]])) pred = comp.sample_predict(features, sample_without_ub) assert pred == { "Lower bound": 50.0, } assert_array_equal(comp.lb_regressor.predict.call_args[0][0], x["Lower bound"]) def test_sample_evaluate(features: Features, sample: TrainingSample) -> None: comp = ObjectiveValueComponent() comp.lb_regressor = Mock(spec=Regressor) comp.lb_regressor.predict = lambda _: np.array([[1.05]]) comp.ub_regressor = Mock(spec=Regressor) comp.ub_regressor.predict = lambda _: np.array([[2.50]]) ev = comp.sample_evaluate(features, sample) assert ev == { "Lower bound": { "Actual value": 1.0, "Predicted value": 1.05, "Absolute error": 0.05, "Relative error": 0.05, }, "Upper bound": { "Actual value": 2.0, "Predicted value": 2.50, "Absolute error": 0.5, "Relative error": 0.25, }, } def test_usage() -> None: solver = LearningSolver(components=[ObjectiveValueComponent()]) instance = get_knapsack_instance(GurobiPyomoSolver()) solver.solve(instance) solver.fit([instance]) stats = solver.solve(instance) assert stats["Lower bound"] == stats["Objective: Predicted LB"] assert stats["Upper bound"] == stats["Objective: Predicted UB"]