First working solution with local search. Close neighborhood.
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590e6713d1
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18a7f784c3
@ -1,95 +1,172 @@
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#!/usr/bin/env python3
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import math
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import logging
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from collections import namedtuple
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Point = namedtuple("Point", ['x', 'y'])
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Facility = namedtuple("Facility", ['index', 'setup_cost', 'capacity', 'location'])
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Customer = namedtuple("Customer", ['index', 'demand', 'location'])
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length = None
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EPSILON = 0.001
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class Length(object):
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""" Length is a helper object o get the distance between
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customers and facilities. It also has functions
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to return the facilities that are closest to a customer. """
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def __init__(self, facilities, customers):
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self.customer_to_facility = [[self.length(c.location, f.location)
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for f in facilities]
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for c in customers]
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self.customer_closes_facility = [sorted([f for f in facilities],
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key=lambda f: self.get(c, f))
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for c in customers]
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def get(self, customer, facility):
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c_idx = customer.index if type(customer) is Customer else customer
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f_idx = facility.index if type(facility) is Facility else facility
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return self.customer_to_facility[c_idx][f_idx]
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def length(self, point1, point2):
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return math.sqrt((point1.x - point2.x)**2 + (point1.y - point2.y)**2)
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def get_facilities(self, customer):
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""" Returns closest facility in increasing order of distance. """
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return self.customer_closes_facility[customer.index]
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def get_feasible_facilities(self, customer, facilities):
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return (f for f in self.get_facilities(customer)
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if f.remaining_capacity >= customer.demand)
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def get_feasible_open_facilities(self, customer, facilities):
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return (f for f in self.get_facilities(customer)
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if f.remaining_capacity >= customer.demand
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if f.is_open)
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class Facility(object):
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def __init__(self, index, setup_cost, capacity, location):
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self.index = index
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self.setup_cost = setup_cost
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self.capacity = capacity
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self.location = location
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self.is_open = False
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self.remaining_capacity = capacity
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self.customers = set()
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def remove(self, customer):
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logging.debug(f"From {self} remove {customer}.")
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if not customer in self.customers:
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raise ValueError(f"{customer} not connected to {self}.")
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delta = 0
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self.customers.remove(customer)
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self.remaining_capacity += customer.demand
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customer.facility = None
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if not self.customers and self.is_open:
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logging.debug(f"{self} is empty but open.")
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delta -= length.get(customer.index, self.index)
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return delta
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def add(self, customer):
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logging.debug(f"To {self} add {customer}.")
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if not self.is_open:
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raise ValueError(f"Cannot connect {customer} to not open {self}.")
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if customer.demand > self.remaining_capacity:
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raise ValueError(f"Capacity of {self} too low for {customer}")
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delta = 0
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if (other_facility := customer.facility):
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delta += other_facility.remove(customer)
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self.remaining_capacity -= customer.demand
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self.customers.add(customer)
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delta += length.get(customer.index, self.index)
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customer.facility = self
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return delta
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def set_open(self):
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logging.debug(f"Open {self}.")
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self.is_open = True
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return self.setup_cost
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def set_not_open(self):
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logging.debug(f"Close {self}.")
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delta = 0
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if self.customers:
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raise ValueError(f"Cannot close {self} with {self.customers}.")
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self.is_open = False
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return -self.setup_cost
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def remove_all_and_close(self):
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logging.debug(f"{self} remove all and close.")
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delta = 0
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for customer in list(self.customers):
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delta += self.remove(customer)
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delta += self.set_not_open()
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return delta
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def __str__(self):
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cap = f"{self.remaining_capacity}/{self.capacity}"
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status = "O" if self.is_open else "C"
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s = f"F({self.index}, {cap}, {status}, {self.setup_cost})"
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return s
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def __repr__(self):
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return self.__str__()
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class Customer(object):
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def __init__(self, index, demand, location):
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self.index = index
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self.demand = demand
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self.location = location
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self.facility = None
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def __str__(self):
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con = "C" if self.facility is not None else "NC!"
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s = f"C({self.index}, {con})"
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return s
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def __repr__(self):
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return self.__str__()
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class Solution(object):
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def __init__(self, facilities, customers):
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self.facilities = facilities
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self.customers = customers
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self.fs = facilities
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self.cs = customers
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self.cost = 0
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self.facility_connected_customers = [set() for _ in facilities]
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self.facility_remaining_capacity = [f.capacity for f in facilities]
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self.customer_to_facility = [None for _ in customers]
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def connect(self, customer_index, facility_index):
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customer = self.customers[customer_index]
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facility = self.facilities[facility_index]
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def validate(self):
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cost = 0
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# If customers is already connected handle disconnect properly.
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if (connected_facitlity_index := self.customer_to_facility[customer_index]):
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self.disconnect(customer_index, connected_facitlity_index)
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for c in self.cs:
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if c.facility is None:
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raise Exception(f"{c} not connected.")
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cost += length.get(c.index, c.facility.index)
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# If facility is currently not used we have to set it up.
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if not self.facility_connected_customers[facility_index]:
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self.cost += facility.setup_cost
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for f in self.fs:
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if f.remaining_capacity < 0:
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raise Exception(f"{f} exceeds capacity.")
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self.facility_connected_customers[facility_index].add(customer_index)
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if self.facility_remaining_capacity[facility_index] < customer.demand:
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raise Exception(f"Cannot connect {customer} to {facility}.")
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self.facility_remaining_capacity[facility_index] -= customer.demand
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if f.customers and not f.is_open:
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raise Exception(f"{f} has customers, but is not open.")
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self.customer_to_facility[customer_index] = facility_index
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self.cost += length(facility.location, customer.location)
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if not f.customers and f.is_open:
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raise Exception(f"{f} has no customers, but is open.")
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def disconnect(self, customer_index, facility_index):
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customer = self.customers[customer_index]
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facility = self.facilities[facility_index]
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self.cost -= length(facility.location, customer.location)
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if f.is_open:
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cost += f.setup_cost
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self.facility_connected_customers[facility_index].remove(customer_index)
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self.facility_remaining_capacity[facility_index] += customer.demand
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if abs(cost - self.cost) > EPSILON:
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raise Exception(f"Running cost {self.cost} unequal to {cost}.")
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self.customer_to_facility[customer_index] = None
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if not self.facility_connected_customers[facility_index]:
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self.cost -= self.facilities[facility_index].setup_cost
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def get_feasible_facilities(self, customer_index):
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customer = self.customers[customer_index]
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facility_indices = [f.index
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for f in self.facilities
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if self.facility_remaining_capacity[f.index] >= customer.demand]
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if not facility_indices:
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raise Exception("No feasible facilities.")
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def key(facility_index):
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cost = 0
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facility = self.facilities[facility_index]
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# If there are customers yet we have to open it.
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if not self.facility_connected_customers[facility_index]:
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cost += facility.setup_cost
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cost += length(customer.location, facility.location)
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return cost
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facility_indices.sort(key=key)
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return facility_indices
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def is_valid(self):
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for customer in self.customers:
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if self.customer_to_facility[customer.index] is None:
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raise Exception(f"{customer} not connected.")
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for facility in self.facilities:
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if self.facility_remaining_capacity[facility.index] < 0:
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raise Exception(f"{facility} exceeds capacity.")
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cost = sum([f.setup_cost
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for f in self.facilities
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if self.facility_connected_customers[f.index]])
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for customer in self.customers:
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facility = self.facilities[self.customer_to_facility[customer.index]]
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cost += length(facility.location, customer.location)
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if abs(cost - self.cost) > 0.00001:
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raise Exception(f"Running cost {self.cost} unequal to actual cost {cost}.")
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return True
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def plot_map(self):
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@ -101,76 +178,133 @@ class Solution(object):
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figure = plt.figure()
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for f in self.facilities:
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for f in self.fs:
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x, y = f.location
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color = 'ro' if self.facility_connected_customers[f.index] else 'go'
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color = 'ro' if f.is_open else 'go'
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plt.plot(x, y, color)
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rem_cap = self.facility_remaining_capacity[f.index]
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plt.text(x, y, f" F({f.index}, {f.setup_cost}, {rem_cap}/{f.capacity})")
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plt.text(x, y, f"{f}")
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for c in self.customers:
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for c in self.cs:
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x, y = c.location
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plt.plot(x, y, 'bx')
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plt.text(x, y, f" C({c.index}, {c.demand})")
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if (f_index := self.customer_to_facility[c.index]) is not None:
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f = self.facilities[f_index]
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plt.text(x, y, f"{c}")
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if (f := c.facility) is not None:
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x_f, y_f = f.location
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plt.plot([x, x_f], [y, y_f], 'b-')
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plt.show()
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def get_facilities_by_customers(self):
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facility_indices = [f.index for f in self.facilities
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if self.facility_connected_customers[f.index]]
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def key(facility_index):
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return len(self.facility_connected_customers[facility_index])
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facility_indices.sort(key=key)
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return facility_indices
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def to_output_data(self):
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# calculate the cost of the solution
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self.is_valid()
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self.validate()
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obj = self.cost
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customer_to_facility = [c.facility.index for c in self.cs]
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# prepare the solution in the specified output format
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output_data = '%.2f' % obj + ' ' + str(0) + '\n'
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output_data += ' '.join(map(str, self.customer_to_facility))
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output_data += ' '.join(map(str, customer_to_facility))
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return output_data
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def build_trivial(self):
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facility = self.fs[0]
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self.cost += facility.set_open()
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for customer in self.cs:
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if facility.remaining_capacity < customer.demand:
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facility = self.fs[facility.index + 1]
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self.cost += facility.set_open()
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self.cost += facility.add(customer)
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return self
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def length(point1, point2):
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return math.sqrt((point1.x - point2.x)**2 + (point1.y - point2.y)**2)
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def build_greedy(self):
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def connect_to_closest_facility(customer):
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cost = 0
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for f in length.get_feasible_facilities(customer, self.fs):
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if not f.is_open:
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cost += f.set_open()
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cost += f.add(customer)
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return cost
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raise Exception("No feasible facilities for {customer}.")
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for customer in self.cs:
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self.cost += connect_to_closest_facility(customer)
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return self
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def reconnect_greedy(self, customers):
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delta = 0
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not_connected = []
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def connect_better_facility(customer):
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current_facility = customer.facility
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if current_facility:
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current_length = length.get(customer, current_facility)
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else:
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current_length = float("inf")
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for f in length.get_feasible_open_facilities(customer, self.fs):
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new_length = length.get(customer, f)
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if new_length < current_length:
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logging.debug(f"{f} is better for {customer}.")
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return f.add(customer)
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elif new_length > current_length:
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return 0
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not_connected.append(customer)
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return 0
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delta += sum([connect_better_facility(c) for c in customers])
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return delta, not_connected
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def build_trivial_solution(solution):
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# build a trivial solution
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# pack the facilities one by one until all the customers are served
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facility_index = 0
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for customer in solution.customers:
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if solution.facility_remaining_capacity[facility_index] >= customer.demand:
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solution.connect(customer.index, facility_index)
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def close_facility(self, facility):
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logging.debug(f"Closing {facility}.")
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original_cost = self.cost
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customers = list(facility.customers)
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self.cost += facility.remove_all_and_close()
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delta, not_connected = self.reconnect_greedy(customers)
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self.cost += delta
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if not_connected:
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logging.info("Not all customers connected. Restore.")
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elif self.cost < original_cost:
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delta = original_cost - self.cost
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logging.info(f"Close {facility} resulted in improvement {delta}.")
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return
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else:
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facility_index += 1
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solution.connect(customer.index, facility_index)
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return solution
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logging.debug(f"No improvement. Restore.")
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self.cost += facility.set_open()
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delta, not_connected = self.reconnect_greedy(customers)
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self.cost += delta
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assert(not not_connected)
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assert(abs(original_cost - self.cost) < EPSILON)
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def build_greedy_solution(solution):
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for customer in solution.customers:
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facility_index = solution.get_feasible_facilities(customer.index)[0]
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solution.connect(customer.index, facility_index)
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return solution
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def open_facility(self, facility):
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pass
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def local_search(self):
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fs = [f for f in self.fs if f.is_open]
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fs.sort(key=lambda f: len(f.customers))
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for f in fs:
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self.close_facility(f)
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#fs = [f for f in self.fs if not f.is_open]
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#fs.sort(key=lambda f: f.setup_cost)
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#for
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def solve_it(input_data):
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global length
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facilities, customers = parse(input_data)
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length = Length(facilities, customers)
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solution = Solution(facilities, customers)
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build_greedy_solution(solution)
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solution.plot_map()
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solution.build_greedy()
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solution.reconnect_greedy(solution.cs)
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solution.local_search()
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# solution.plot_map()
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output_data = solution.to_output_data()
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return output_data
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def main():
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file_location = "data/fl_3_1"
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file_location = "data/fl_100_7"
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with open(file_location, 'r') as input_data_file:
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input_data = input_data_file.read()
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print(solve_it(input_data))
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@ -200,5 +334,6 @@ def parse(input_data):
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if __name__ == "__main__":
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logging.basicConfig(level=logging.INFO, format='%(message)s')
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main()
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