Implement FileInstance

tests/instance/test_file.py

@@ -0,0 +1,32 @@
+#  MIPLearn: Extensible Framework for Learning-Enhanced Mixed-Integer Optimization
+#  Copyright (C) 2020-2021, UChicago Argonne, LLC. All rights reserved.
+#  Released under the modified BSD license. See COPYING.md for more details.
+
+import tempfile
+
+from miplearn.solvers.learning import LearningSolver
+from miplearn.solvers.gurobi import GurobiSolver
+from miplearn.features.sample import Hdf5Sample
+from miplearn.instance.file import FileInstance
+
+
+def test_usage() -> None:
+    # Create original instance
+    original = GurobiSolver().build_test_instance_knapsack()
+
+    # Save instance to disk
+    file = tempfile.NamedTemporaryFile()
+    FileInstance.save(original, file.name)
+    sample = Hdf5Sample(file.name)
+    assert len(sample.get_bytes("pickled")) > 0
+
+    # Solve instance from disk
+    solver = LearningSolver(solver=GurobiSolver())
+    solver.solve(FileInstance(file.name))
+
+    # Assert HDF5 contains training data
+    sample = FileInstance(file.name).get_samples()[0]
+    assert sample.get_scalar("mip_lower_bound") == 1183.0
+    assert sample.get_scalar("mip_upper_bound") == 1183.0
+    assert len(sample.get_vector("lp_var_values")) == 5
+    assert len(sample.get_vector("mip_var_values")) == 5