Skip to content
Snippets Groups Projects
Commit 90148e8c authored by Victor Ruelle's avatar Victor Ruelle
Browse files

Replace cvrp.py

parent 2481576b
No related branches found
No related tags found
No related merge requests found
Hide whitespace changes
Inline Side-by-side
Showing
with 61 additions and 69 deletions
cvrp.py
+ 61
− 69
View file @ 90148e8c
...@@ -2,11 +2,10 @@ ...@@ -2,11 +2,10 @@
''' librairies nécéssaires ''' ''' librairies nécéssaires '''
from globals import * from globals import *
from support import pprint from logging_cvrp import *
from support import reset_timer
reset_timer() reset_timer()
if debug: log.write_globals()
print("starting to import necessary librairies...") log.title("starting to import necessary librairies...")
import pyomo.environ as pyo import pyomo.environ as pyo
from pyomo.opt import SolverFactory from pyomo.opt import SolverFactory
from numpy.random import random as rd from numpy.random import random as rd
...@@ -23,8 +22,7 @@ import sys ...@@ -23,8 +22,7 @@ import sys
import cvrpGoogleOpt as google import cvrpGoogleOpt as google
import cbc import cbc
if debug: log.write_timed("finished importing all modules")
pprint("finished importing all modules")
################## ##################
### HYPOTHESIS ### ### HYPOTHESIS ###
...@@ -73,6 +71,8 @@ if pyomo.version.version_info >= (4, 2, 0, '', 0): ...@@ -73,6 +71,8 @@ if pyomo.version.version_info >= (4, 2, 0, '', 0):
### INITIALISATION ### ### INITIALISATION ###
###################### ######################
log.title("initialising model")
''' initalise the solver and the abstract model ''' ''' initalise the solver and the abstract model '''
opt = SolverFactory('glpk') opt = SolverFactory('glpk')
...@@ -144,8 +144,7 @@ instance.c_deg = pyo.Constraint(instance.nodes, rule=support.rule_deg) ...@@ -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 instance.c_cap = pyo.ConstraintList() # on utilise cette structure pour pouvoir ajouter et supprimer des contraintes par la suite
#liste vide pour commencer #liste vide pour commencer
if debug: log.write_timed("finished constructing model")
pprint("finished constructing model")
###################### ######################
...@@ -208,12 +207,11 @@ class instance_manager(): ...@@ -208,12 +207,11 @@ class instance_manager():
def branch(instance,instance_manager): def branch(instance,instance_manager):
#branches instance problem into two complementary sub problem instances over a specific index #branches instance problem into two complementary sub problem instances over a specific index
if debug: log.subtitle("entering branching",instance.id)
pprint(support.list_to_string(instance.id)+"+++++ entering branching")
# we choose the index for branching whose corresponding value is closest to 0.5 # we choose the index for branching whose corresponding value is closest to 0.5
index = -1,-1 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(): 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 #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): ...@@ -225,12 +223,8 @@ def branch(instance,instance_manager):
if index==(-1,-1): if index==(-1,-1):
raise NameError("No branching index found") 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 instance.x[index].fixed = True
instance2 = instance.clone() instance2 = instance.clone()
instance.x[index].value = 0 instance.x[index].value = 0
...@@ -243,17 +237,15 @@ def branch(instance,instance_manager): ...@@ -243,17 +237,15 @@ def branch(instance,instance_manager):
instance.depth = depth+1 instance.depth = depth+1
instance.id = id0+[id.get_and_increment()] instance.id = id0+[id.get_and_increment()]
instance2.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) instance.lower_bound = cbc.lower_bound(instance)
instance2.lower_bound = cbc.lower_bound(instance2) 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(instance)
instance_manager.add(instance2) instance_manager.add(instance2)
...@@ -269,21 +261,25 @@ def column_generation(instance,instance_manager): ...@@ -269,21 +261,25 @@ def column_generation(instance,instance_manager):
#2b : if that solution is also integer, we need not continue this branch! #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 #3) else : add found constraints to constraints list, re-solve linear problem and continue
if debug: log.subtitle("entering column generation",instance.id)
pprint(support.list_to_string(instance.id)+"+++++ entering column generation")
feasible_integer_found = False
loop_count = 1 loop_count = 1
failure_count = 0 obj_val_old = pyo.value(instance.objective)
while support.continue_column_generation(instance,loop_count): while support.continue_column_generation(instance,loop_count):
log.write("column generation loop "+str(loop_count),instance.id)
#we first add capacity constraints #we first add capacity constraints
success, count = constraint.add_c_cap(instance) success, count = constraint.add_c_cap(instance)
connected_threshold.update() log.write_timed("----- we found " +str(count) + " capacity cuts",instance.id)
if debug: if not(success) and support.solution_is_integer(instance):
print(support.list_to_string(instance.id)+"----- we found " +str(count) + " capacity cuts with threshold of " +str(connected_threshold.value)) #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) #remove_inactive_constraints(instance)
...@@ -291,29 +287,24 @@ def column_generation(instance,instance_manager): ...@@ -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) #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 #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): if not(success):
failure_count+=1 instance_manager.record_partial_solution(instance)
if debug: break
print(support.list_to_string(instance.id)+"----- no cutting planes found with threshold of " +str(connected_threshold.value))
if failure_count>len(vals): #resolve instance before reiterating
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
results = opt.solve(instance) 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: #we verify that we are not stuck in an unmoving loop
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") 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 loop_count+=1
return feasible_integer_found
def remove_inactive_constraints(instance): def remove_inactive_constraints(instance):
#must disable constraints that are inactive being careful of the fact that they may become active again later on... #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): ...@@ -326,16 +317,19 @@ def main_loop(instance_manager):
while instance!=None: 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 #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) feasible_integer_found = column_generation(instance,instance_manager)
#if we consider that we have done "enough", we also stop (typically : too many iterations) #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 and apply main_loop to the two new instances
branch(instance,instance_manager) branch(instance,instance_manager)
else : else :
log.write_timed("branch is cut and recorded",instance.id)
instance_manager.record_partial_solution(instance) instance_manager.record_partial_solution(instance)
instance = instance_manager.pop() #will return none if there are no instances left in queue instance = instance_manager.pop() #will return none if there are no instances left in queue
...@@ -343,12 +337,10 @@ def main_loop(instance_manager): ...@@ -343,12 +337,10 @@ def main_loop(instance_manager):
### MAIN ### ### MAIN ###
############ ############
print() log.write("using input file "+file)
print("using input file "+file)
instance.file = file instance.file = file
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))
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()
#computing lower_bound #computing lower_bound
instance.lower_bound = cbc.lower_bound(instance) instance.lower_bound = cbc.lower_bound(instance)
...@@ -357,28 +349,28 @@ instance.lower_bound = cbc.lower_bound(instance) ...@@ -357,28 +349,28 @@ instance.lower_bound = cbc.lower_bound(instance)
instance_manager = instance_manager() instance_manager = instance_manager()
instance_manager.add(instance) 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 #solving the initial instance in order to initialize instance.x values
results = opt.solve(instance) results = opt.solve(instance)
#printing initial value of objective function #printing initial value of objective function
if debug: log.write_spaced("0: initial value of objective function "+str(round(pyo.value(instance.objective),2))+" and is "+str(support.integer_percent(instance))+"% integer")
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 = ""
instance.id = [id.get_and_increment()] instance.id = [id.get_and_increment()]
instance.depth = 0 instance.depth = 0
main_loop(instance_manager) main_loop(instance_manager)
pprint("++++++++++ finished solving") log.title("finished solving")
if instance_manager.best_feasible_integer_solution==None: if instance_manager.best_feasible_integer_solution==None:
print("no optimal integer solution found") log.write("no optimal integer solution found")
print("lower bound found :" +str(pyo.value(instance_manager.partial_solution_recorded[0].objective))) 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: else:
if input("show instance ? (y/n) (yes/no) \n") in ["y","yes","oui","hell","yeah"]: # if input("show instance ? (y/n) (yes/no) \n") in ["y","yes","oui","hell","yeah"]:
instance_manager.best_feasible_integer_solution.display() # 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 ''' ''' testing '''
''' this works well ''' this works well
......
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment