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141 lines
4.7 KiB
141 lines
4.7 KiB
# MIPLearn: Extensible Framework for Learning-Enhanced Mixed-Integer Optimization
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# Copyright (C) 2020-2021, UChicago Argonne, LLC. All rights reserved.
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# Released under the modified BSD license. See COPYING.md for more details.
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from typing import Hashable, Dict
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from unittest.mock import Mock
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import numpy as np
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import pytest
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from numpy.testing import assert_array_equal
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from miplearn.classifiers import Regressor
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from miplearn.components.objective import ObjectiveValueComponent
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from miplearn.features.sample import Sample, MemorySample
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from miplearn.solvers.learning import LearningSolver
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from miplearn.solvers.pyomo.gurobi import GurobiPyomoSolver
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@pytest.fixture
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def sample() -> Sample:
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sample = MemorySample(
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{
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"mip_lower_bound": 1.0,
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"mip_upper_bound": 2.0,
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"lp_instance_features": [1.0, 2.0, 3.0],
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},
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)
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return sample
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def test_sample_xy(sample: Sample) -> None:
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x_expected = {
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"Lower bound": [[1.0, 2.0, 3.0]],
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"Upper bound": [[1.0, 2.0, 3.0]],
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}
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y_expected = {
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"Lower bound": [[1.0]],
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"Upper bound": [[2.0]],
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}
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xy = ObjectiveValueComponent().sample_xy(None, sample)
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assert xy is not None
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x_actual, y_actual = xy
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assert x_actual == x_expected
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assert y_actual == y_expected
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def test_fit_xy() -> None:
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x: Dict[Hashable, np.ndarray] = {
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"Lower bound": np.array([[0.0, 0.0], [1.0, 2.0]]),
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"Upper bound": np.array([[0.0, 0.0], [1.0, 2.0]]),
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}
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y: Dict[Hashable, np.ndarray] = {
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"Lower bound": np.array([[100.0]]),
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"Upper bound": np.array([[200.0]]),
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}
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reg = Mock(spec=Regressor)
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reg.clone = Mock(side_effect=lambda: Mock(spec=Regressor))
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comp = ObjectiveValueComponent(regressor=reg)
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assert "Upper bound" not in comp.regressors
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assert "Lower bound" not in comp.regressors
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comp.fit_xy(x, y)
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assert reg.clone.call_count == 2
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assert "Upper bound" in comp.regressors
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assert "Lower bound" in comp.regressors
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assert comp.regressors["Upper bound"].fit.call_count == 1 # type: ignore
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assert comp.regressors["Lower bound"].fit.call_count == 1 # type: ignore
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assert_array_equal(
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comp.regressors["Upper bound"].fit.call_args[0][0], # type: ignore
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x["Upper bound"],
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)
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assert_array_equal(
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comp.regressors["Lower bound"].fit.call_args[0][0], # type: ignore
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x["Lower bound"],
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)
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assert_array_equal(
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comp.regressors["Upper bound"].fit.call_args[0][1], # type: ignore
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y["Upper bound"],
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)
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assert_array_equal(
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comp.regressors["Lower bound"].fit.call_args[0][1], # type: ignore
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y["Lower bound"],
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)
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def test_sample_predict(sample: Sample) -> None:
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x, y = ObjectiveValueComponent().sample_xy(None, sample)
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comp = ObjectiveValueComponent()
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comp.regressors["Lower bound"] = Mock(spec=Regressor)
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comp.regressors["Upper bound"] = Mock(spec=Regressor)
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comp.regressors["Lower bound"].predict = Mock( # type: ignore
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side_effect=lambda _: np.array([[50.0]])
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)
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comp.regressors["Upper bound"].predict = Mock( # type: ignore
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side_effect=lambda _: np.array([[60.0]])
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)
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pred = comp.sample_predict(sample)
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assert pred == {
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"Lower bound": 50.0,
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"Upper bound": 60.0,
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}
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assert_array_equal(
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comp.regressors["Upper bound"].predict.call_args[0][0], # type: ignore
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x["Upper bound"],
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)
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assert_array_equal(
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comp.regressors["Lower bound"].predict.call_args[0][0], # type: ignore
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x["Lower bound"],
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)
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def test_sample_evaluate(sample: Sample) -> None:
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comp = ObjectiveValueComponent()
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comp.regressors["Lower bound"] = Mock(spec=Regressor)
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comp.regressors["Lower bound"].predict = lambda _: np.array([[1.05]]) # type: ignore
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comp.regressors["Upper bound"] = Mock(spec=Regressor)
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comp.regressors["Upper bound"].predict = lambda _: np.array([[2.50]]) # type: ignore
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ev = comp.sample_evaluate(None, sample)
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assert ev == {
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"Lower bound": {
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"Actual value": 1.0,
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"Predicted value": 1.05,
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"Absolute error": 0.05,
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"Relative error": 0.05,
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},
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"Upper bound": {
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"Actual value": 2.0,
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"Predicted value": 2.50,
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"Absolute error": 0.5,
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"Relative error": 0.25,
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},
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}
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def test_usage() -> None:
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solver = LearningSolver(components=[ObjectiveValueComponent()])
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instance = GurobiPyomoSolver().build_test_instance_knapsack()
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solver.solve(instance)
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solver.fit([instance])
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stats = solver.solve(instance)
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assert stats["mip_lower_bound"] == stats["Objective: Predicted lower bound"]
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assert stats["mip_upper_bound"] == stats["Objective: Predicted upper bound"]
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