88 lines
3.5 KiB
Python
88 lines
3.5 KiB
Python
from pulp import lpSum, LpProblem
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from random import randint, sample
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import logging
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from models.bundle import Bundle
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from models.solver_run import SolverRun
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from models.item import Item
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from lib.errors.item_generation_error import ItemGenerationError
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def build_constraints(solver_run: SolverRun, problem: LpProblem,
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items: list[Item], bundles: list[Bundle]) -> LpProblem:
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logging.info('Creating Constraints...')
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try:
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total_form_items = solver_run.total_form_items
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constraints = solver_run.constraints
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for constraint in constraints:
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attribute = constraint.reference_attribute
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min = constraint.minimum
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max = constraint.maximum
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if attribute.type == 'metadata':
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logging.info('Metadata Constraint Generating...')
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con = dict(
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zip([item.id for item in solver_run.items], [
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item.attribute_exists(attribute)
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for item in solver_run.items
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]))
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problem += lpSum([
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con[item.id] * items[item.id] for item in solver_run.items
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]) >= round(
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total_form_items *
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(min / 100)), f'{attribute.id} - {attribute.value} - min'
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problem += lpSum([
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con[item.id] * items[item.id] for item in solver_run.items
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]) <= round(
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total_form_items *
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(max / 100)), f'{attribute.id} - {attribute.value} - max'
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elif attribute.type == 'bundle':
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logging.info('Bundles Constraint Generating...')
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# TODO: account for many different bundle types, since the id condition in L33 could yield duplicates
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if solver_run.bundles != None:
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# make sure the total bundles used in generated form is limited between min-max set
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problem += lpSum([
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bundles[bundle.id] for bundle in solver_run.bundles
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]) == randint(int(constraint.minimum),
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int(constraint.maximum))
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logging.info('Constraints Created...')
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return problem
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except ValueError as error:
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logging.error(error)
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raise ItemGenerationError(
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"Bundle min and/or max larger than bundle amount provided",
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error.args[0])
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def get_random_bundles(total_form_items: int,
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bundles: list[Bundle],
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min: int,
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max: int,
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found_bundles=False) -> list[Bundle]:
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selected_bundles = None
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total_bundle_items = 0
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total_bundles = randint(min, max)
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logging.info(f'Selecting Bundles (total of {total_bundles})...')
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while found_bundles == False:
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selected_bundles = sample(bundles, total_bundles)
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total_bundle_items = sum(bundle.count for bundle in selected_bundles)
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if total_bundle_items <= total_form_items:
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found_bundles = True
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if found_bundles == True:
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return selected_bundles
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else:
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return get_random_bundles(total_form_items, total_bundles - 1, bundles)
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def elasticize_constraint(lp_constraint, parameters = {}):
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penalty = parameters.get('penalty', 1) # could be a 100% penalty
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proportionFreeBound = parameters.get('proportionFreeBound', 0.25)
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return lp_constraint.makeElasticSubProblem(penalty=penalty, proportionFreeBound=proportionFreeBound)
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