opt2 added as an option

Author: sebdelsol

aco.py

@@ -18,7 +18,7 @@ class ACO:
 
     name = 'ACO'
 
-    def __init__(self, graph, nAnts = 10 , doPlot = True, multiprocess = True, nProfile = 0):
+    def __init__(self, graph, nAnts = 10 , opt2=False, doPlot = True, multiprocess = True, nProfile = 0):
         # reset seed to have 'true' random
         random.seed()
         np.random.seed()
@@ -46,7 +46,7 @@ def __init__(self, graph, nAnts = 10 , doPlot = True, multiprocess = True, nProf
         createPool = Pool if multiprocess else DummyPool
 
         # create a pool of processes of workers
-        args = (nNodes, log,
+        args = (nNodes, log, opt2,
                 SharedMatWorker(graph.sharedMatDist),
                 SharedMatWorker(graph.sharedMatWeight),
                 SharedMatWorker(sharedPaths))
@@ -129,7 +129,7 @@ def do_step(self, step):
 
     def simulate(self, nStep=200, alpha=1.0,
                  beta=3.0, rho=.1, tau=1.0, q=.6,
-                 nAvg=10, termination = True):
+                 nAvg=10, termination=True):
 
         log (f'simulate {nStep} steps')
 

graphMap.py

@@ -14,7 +14,7 @@ class GraphMAP(Graph):
 
     cachedir = 'cache'
 
-    def __init__(self, nNodes = 50, seed = 1000, address = 'Nimes, France',
+    def __init__(self, nNodes = 50, seed = 1000, address = 'Montpellier, France',
                  radius = 1500, ntype = 'drive', footprints = True, folium = False):
 
         # imports only when the class is intancied

main.py

@@ -35,7 +35,7 @@
     # [0] = GraphRND
     # [1] = GraphTSP
     # [2] = GraphMAP
-    GraphCls = GraphClasses[1]
+    GraphCls = GraphClasses[0]
     gclsname = GraphCls.__name__
 
     if gclsname == 'GraphRND':
@@ -69,6 +69,7 @@
         acoCls = AcoClasses[2]
 
         acokwargs = dict(nAnts        = graph.nNodes,
+                         opt2         = False,
                          doPlot       = True,
                          multiprocess = True,
                          nProfile     = 0)

mainhelper.py

@@ -45,8 +45,9 @@ def print_defaults(txt, func, override = None):
     key_val = get_defaults(func)
 
     if override is not None:
-        key_val = [(k, override.get(k, v)) for k, v in key_val]
+        key_val = ((k, override.get(k, v)) for k, v in key_val)
 
+    key_val = list(key_val)
     width = max(len(k) for k, v in key_val)
     args = (f'{k}'.ljust(width) + f' = {v}' for k, v in key_val)
 
@@ -58,7 +59,7 @@ def print_defaults(txt, func, override = None):
 def copy_paste_helper():
     log ('TO COPY PASTE !')
     tab ('# generated with mainhelper.py')
-    tab ('from mainHelper import GraphClasses, TspOpts, AcoClasses')
+    tab ('from mainhelper import GraphClasses, TspOpts, AcoClasses')
     print ()
     for i, gtype in enumerate(GraphClasses):
         tab (f'# [{i}] = {gtype.__name__}')

worker.py

@@ -46,9 +46,10 @@ def update(self, mat):
 class Worker:
 
     @staticmethod
-    def init(nNodes, log, sharedMatDist, sharedMatWeight, sharedPaths):
+    def init(nNodes, log, opt2, sharedMatDist, sharedMatWeight, sharedPaths):
         Worker.nNodes = nNodes
         Worker.log = log
+        Worker.opt2 = opt2
 
         # sharedMatDist, sharedMatWeight and sharedPaths are shared in memory by all processes
         Worker.MatDist = sharedMatDist.get()       # read only
@@ -113,8 +114,28 @@ def ant_do_tour(ant, start, q):
         # back to the start
         path[-1] = start
 
-        # path length rounded with 2 digits, since equivalent paths (by rotation or inversion)
-        # might have slightly different lengths due to the sum imprecision
         # rows = (array 'from nodes'), columns = (array 'to nodes') of the path
         rows, cols = path[:-1], path[1:]
-        return round(Worker.MatDist[rows, cols].sum(), 2)
+        length = Worker.MatDist[rows, cols].sum()
+
+        # 2-opt permutations to find a better path
+        # optims for symmetric path
+        if Worker.opt2:
+            dist = Worker.MatDist
+
+            for i in range(1, nNodes):
+                for j in range(i + 1, nNodes):
+
+                    pi, pj, piprev, pjnext = path[i], path[j], path[i-1], path[j+1]
+                    gain = dist[pi][pjnext] + dist[piprev][pj] - dist[piprev][pi] - dist[pj][pjnext]
+
+                    if gain < 0:
+                        # invert i,j and everything in between
+                        path[i:j+1] = path[j:i-1:-1]
+
+                        # add the gain
+                        length += gain
+
+        # path length rounded with 2 digits, since equivalent paths (by rotation or inversion)
+        # might have slightly different lengths due to the sum imprecision
+        return round(length, 2)