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Commit 90148e8c authored by Victor Ruelle's avatar Victor Ruelle
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Replace cvrp.py

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cvrp.py
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......@@ -2,11 +2,10 @@
''' librairies nécéssaires '''
from globals import *
from support import pprint
from support import reset_timer
from logging_cvrp import *
reset_timer()
if debug:
print("starting to import necessary librairies...")
log.write_globals()
log.title("starting to import necessary librairies...")
import pyomo.environ as pyo
from pyomo.opt import SolverFactory
from numpy.random import random as rd
......@@ -23,8 +22,7 @@ import sys
import cvrpGoogleOpt as google
import cbc
if debug:
pprint("finished importing all modules")
log.write_timed("finished importing all modules")
##################
### HYPOTHESIS ###
......@@ -73,6 +71,8 @@ if pyomo.version.version_info >= (4, 2, 0, '', 0):
### INITIALISATION ###
######################
log.title("initialising model")
''' initalise the solver and the abstract model '''
opt = SolverFactory('glpk')
......@@ -144,8 +144,7 @@ instance.c_deg = pyo.Constraint(instance.nodes, rule=support.rule_deg)
instance.c_cap = pyo.ConstraintList() # on utilise cette structure pour pouvoir ajouter et supprimer des contraintes par la suite
#liste vide pour commencer
if debug:
pprint("finished constructing model")
log.write_timed("finished constructing model")
######################
......@@ -208,12 +207,11 @@ class instance_manager():
def branch(instance,instance_manager):
#branches instance problem into two complementary sub problem instances over a specific index
if debug:
pprint(support.list_to_string(instance.id)+"+++++ entering branching")
log.subtitle("entering branching",instance.id)
# we choose the index for branching whose corresponding value is closest to 0.5
index = -1,-1
dist = 1 # max theoretical dist for bridges considered is actually 0.5
dist = 1 # initialised at max value (actually max is 0.5 but oh well)
for bridge in instance.x.keys():
#do not consider bridge with depot for their bound is (0,2) and we would have to branch over 3 instances
......@@ -225,12 +223,8 @@ def branch(instance,instance_manager):
if index==(-1,-1):
raise NameError("No branching index found")
if debug:
pprint(support.list_to_string(instance.id)+"----- branching done over index "+str(index)+" with value "+str(instance.x[index].value))
#creating new instances ! recycling the old one into one of the branches
#creating new instances ! recycling the old one into one of the new branches
instance.x[index].fixed = True
instance2 = instance.clone()
instance.x[index].value = 0
......@@ -243,17 +237,15 @@ def branch(instance,instance_manager):
instance.depth = depth+1
instance.id = id0+[id.get_and_increment()]
instance2.id = id0+[id.get_and_increment()]
if debug:
log = instance.log
instance.log = log+str(index)+" : 0 / "
instance.log = log+str(index)+" : 1 / "
print(support.list_to_string(id0)+"----- new value of objective function for instance "+str(instance.id[-1])+" fixed 0 : "+str(round(pyo.value(instance.objective),2)))
pprint(support.list_to_string(id0)+"----- new value of objective function for instance "+str(instance2.id[-1])+" fixed 1 : "+str(round(pyo.value(instance2.objective),2)))
instance.lower_bound = cbc.lower_bound(instance)
instance2.lower_bound = cbc.lower_bound(instance2)
log.write_timed("branching found over index "+str(index)+" with value "+str(instance.x[index].value),instance.id)
log.write("value of objective function for new instance "+str(instance.id[-1])+" which fixed variable at 0 is "+str(round(pyo.value(instance.objective),2)),id0)
log.write("value of objective function for new instance "+str(instance2.id[-1])+" which fixed variable at 1 is "+str(round(pyo.value(instance2.objective),2)),id0)
instance_manager.add(instance)
instance_manager.add(instance2)
......@@ -269,21 +261,25 @@ def column_generation(instance,instance_manager):
#2b : if that solution is also integer, we need not continue this branch!
#3) else : add found constraints to constraints list, re-solve linear problem and continue
if debug:
pprint(support.list_to_string(instance.id)+"+++++ entering column generation")
log.subtitle("entering column generation",instance.id)
feasible_integer_found = False
loop_count = 1
failure_count = 0
obj_val_old = pyo.value(instance.objective)
while support.continue_column_generation(instance,loop_count):
log.write("column generation loop "+str(loop_count),instance.id)
#we first add capacity constraints
success, count = constraint.add_c_cap(instance)
connected_threshold.update()
success, count = constraint.add_c_cap(instance)
log.write_timed("----- we found " +str(count) + " capacity cuts",instance.id)
if debug:
print(support.list_to_string(instance.id)+"----- we found " +str(count) + " capacity cuts with threshold of " +str(connected_threshold.value))
if not(success) and support.solution_is_integer(instance):
#the solution found is valid and integer --> optimal within the branch
feasible_integer_found = True
instance_manager.record_feasible_integer_solution(instance)
log.write("feasible integer solution found with objective value of "+str(round(pyo.value(instance.objective),2)),instance.id)
#in the future : add other constraints
#we add other constraints : multi_start,comb... success boolean is update at each new heuristic
#remove_inactive_constraints(instance)
......@@ -291,29 +287,24 @@ def column_generation(instance,instance_manager):
#ATTENTION : for feasible_integer_found to be true we only need to verify is_integer and connected components heuristic (not all other constraint generation heuristics)
#therefore, when adding new heursitics in the future, this breaking condition will have to be placed else where to happen also right after said heuristic
if not(success):
failure_count+=1
if debug:
print(support.list_to_string(instance.id)+"----- no cutting planes found with threshold of " +str(connected_threshold.value))
if failure_count>len(vals):
if support.solution_is_integer(instance):
instance_manager.record_feasible_integer_solution(instance)
if debug :
print(support.list_to_string(instance.id)+"----- feasible solution found during column generation is integer!")
print(support.list_to_string(instance.id)+"----- branch is recorded and cut")
print(support.list_to_string(instance.id)+"----- value of objective function for solution is "+str(round(pyo.value(instance.objective),2)))
print()
else:
instance_manager.record_partial_solution(instance)
break
else:
failure_count = 0
instance_manager.record_partial_solution(instance)
break
#resolve instance before reiterating
results = opt.solve(instance)
obj_val = pyo.value(instance.objective)
log.write( "objective function after loop "+str(loop_count)+" : "+str(round(obj_val,4))+" ( "+str(support.integer_percent(instance))+"% integer )",instance.id)
if debug:
pprint( support.list_to_string(instance.id)+"----- value of objective function during column generation "+str(loop_count)+" is "+str(round(pyo.value(instance.objective),10))+" and is "+str(support.integer_percent(instance))+"% integer")
#we verify that we are not stuck in an unmoving loop
if abs(obj_val-obj_val_old)<0.00000001 :
log.write("no evolution in column_generation, moving on to branching",instance.id)
break
obj_val_old = obj_val
loop_count+=1
return feasible_integer_found
def remove_inactive_constraints(instance):
#must disable constraints that are inactive being careful of the fact that they may become active again later on...
......@@ -326,16 +317,19 @@ def main_loop(instance_manager):
while instance!=None:
log.subtitle("starting processing of new instance with lower_bound of "+str(instance.lower_bound),instance.id)
#adding constriants and resolving and verifying if we have, by chance, found an integer and feasible solution
feasible_integer_found = column_generation(instance,instance_manager)
#if we consider that we have done "enough", we also stop (typically : too many iterations)
if instance.depth < max_depth and support.max_time_not_reached() and instance_manager.best_feasible_integer_solution==None:
if instance.depth < max_depth and max_time_not_reached() and instance_manager.best_feasible_integer_solution==None:
#branch and apply main_loop to the two new instances
branch(instance,instance_manager)
else :
log.write_timed("branch is cut and recorded",instance.id)
instance_manager.record_partial_solution(instance)
instance = instance_manager.pop() #will return none if there are no instances left in queue
......@@ -343,12 +337,10 @@ def main_loop(instance_manager):
### MAIN ###
############
print()
print("using input file "+file)
log.write("using input file "+file)
instance.file = file
print()
print("++++++++++ starting CVRP solving for "+str(instance.n.value)+" nodes, "+str(instance.number_of_vehicles.value)+" vehicles with capacity of "+str(instance.capacity.value))
print()
log.title("starting CVRP solving for "+str(instance.n.value)+" nodes, "+str(instance.number_of_vehicles.value)+" vehicles with capacity of "+str(instance.capacity.value))
#computing lower_bound
instance.lower_bound = cbc.lower_bound(instance)
......@@ -357,28 +349,28 @@ instance.lower_bound = cbc.lower_bound(instance)
instance_manager = instance_manager()
instance_manager.add(instance)
log.write("initial upper bound of cvrp problem is "+str(instance_manager.upper_bound))
#solving the initial instance in order to initialize instance.x values
results = opt.solve(instance)
#printing initial value of objective function
if debug:
print("0----- initial value of objective function "+str(round(pyo.value(instance.objective),2))+" and is "+str(support.integer_percent(instance))+"% integer")
print()
instance.log = ""
log.write_spaced("0: initial value of objective function "+str(round(pyo.value(instance.objective),2))+" and is "+str(support.integer_percent(instance))+"% integer")
instance.id = [id.get_and_increment()]
instance.depth = 0
main_loop(instance_manager)
pprint("++++++++++ finished solving")
log.title("finished solving")
if instance_manager.best_feasible_integer_solution==None:
print("no optimal integer solution found")
print("lower bound found :" +str(pyo.value(instance_manager.partial_solution_recorded[0].objective)))
log.write("no optimal integer solution found")
log.write("best lower bound found :" +str(pyo.value(instance_manager.partial_solution_recorded[0].objective))+" and is "+str(support.integer_percent(instance_manager.partial_solution_recorded[0]))+"% integer")
else:
if input("show instance ? (y/n) (yes/no) \n") in ["y","yes","oui","hell","yeah"]:
instance_manager.best_feasible_integer_solution.display()
# if input("show instance ? (y/n) (yes/no) \n") in ["y","yes","oui","hell","yeah"]:
# instance_manager.best_feasible_integer_solution.display()
log.write("best feaible integer solution found has objective value of "+str(pyo.value(instance_manager.best_feasible_integer_solution.objective)))
with open(log.full,'a') as f:
print(instance_manager.best_feasible_integer_solution.display(),file = f)
''' testing '''
''' this works well
......
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