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64 lines
2.6 KiB
64 lines
2.6 KiB
# MIPLearn, an extensible framework for Learning-Enhanced Mixed-Integer Optimization
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# Copyright (C) 2019-2020 Argonne National Laboratory. All rights reserved.
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# Written by Alinson S. Xavier <axavier@anl.gov>
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from . import Component
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from .transformers import PerVariableTransformer
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from abc import ABC, abstractmethod
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import numpy as np
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class BranchPriorityComponent(Component):
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def __init__(self,
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initial_priority=None,
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collect_training_data=True):
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self.priority = initial_priority
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self.transformer = PerVariableTransformer()
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self.collect_training_data = collect_training_data
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def before_solve(self, solver, instance, model):
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assert solver.is_persistent, "BranchPriorityComponent requires a persistent solver"
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var_split = self.transformer.split_variables(instance, model)
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for category in var_split.keys():
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var_index_pairs = var_split[category]
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if self.priority is not None:
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from gurobipy import GRB
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for (i, (var, index)) in enumerate(var_index_pairs):
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gvar = solver.internal_solver._pyomo_var_to_solver_var_map[var[index]]
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gvar.setAttr(GRB.Attr.BranchPriority, int(self.priority[index]))
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def after_solve(self, solver, instance, model):
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if self.collect_training_data:
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import subprocess, tempfile, os
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src_dirname = os.path.dirname(os.path.realpath(__file__))
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model_file = tempfile.NamedTemporaryFile(suffix=".lp")
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priority_file = tempfile.NamedTemporaryFile()
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solver.internal_solver.write(model_file.name)
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subprocess.run(["julia",
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"%s/scripts/branchpriority.jl" % src_dirname,
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model_file.name,
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priority_file.name],
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check=True,
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capture_output=True)
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self._merge(np.genfromtxt(priority_file.name,
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delimiter=',',
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dtype=np.float64))
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def fit(self, solver):
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pass
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def merge(self, other):
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if other.priority is not None:
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self._merge(other.priority)
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def _merge(self, priority):
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assert isinstance(priority, np.ndarray)
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if self.priority is None:
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self.priority = priority
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else:
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assert self.priority.shape == priority.shape
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self.priority += priority |