optimize calculate_td_vdf() in Link

- remove demand_periods from its arg list to have one unified implementation;
- store reduction_ratio in VDFPeriod and update run_bpr() accordingly;
- add set_reduction_ratio() in Link to set up reduction_ratio for each
  VDFPeriod;
- remove beg_iter and end_iter from SpecialEvent, and update its constructor;
- update read_settings() accordingly.

docs/source/conf.py

@@ -26,7 +26,7 @@
 author = 'Dr. Peiheng Li and Dr. Xuesong (Simon) Zhou'
 
 # The full version, including alpha/beta/rc tags
-release = 'v0.9.2'
+release = 'v0.9.3'
 
 
 # -- General configuration ---------------------------------------------------

path4gmns/classes.py

@@ -173,27 +173,21 @@ def reset_period_flow_vol(self):
     def increase_period_flow_vol(self, tau, fv):
         self.flow_vol_by_period[tau] += fv
 
-    def calculate_td_vdf(self, demand_periods=None):
-        if demand_periods is None:
-            for tau in range(self.demand_period_size):
-                self.travel_time_by_period[tau] = (
-                    self.vdfperiods[tau].run_bpr(self.flow_vol_by_period[tau])
-                )
-        else:
-            for dp in demand_periods:
-                tau = dp.get_id()
-                reduction_ratio = dp.get_reduction_ratio(self.id)
-                self.travel_time_by_period[tau] = (
-                    self.vdfperiods[tau].run_bpr(self.flow_vol_by_period[tau],
-                                                 reduction_ratio)
-                )
+    def calculate_td_vdf(self):
+        for tau in range(self.demand_period_size):
+            self.travel_time_by_period[tau] = (
+                self.vdfperiods[tau].run_bpr(self.flow_vol_by_period[tau])
+            )
 
     def update_waiting_time(self, minute, wt):
         try:
             self.waiting_time[minute] += wt
         except IndexError:
             pass
 
+    def set_reduction_ratio(self, tau, rr):
+        self.vdfperiods[tau].reduction_ratio = rr
+
 
 class Agent:
     """ individual agent derived from aggregated demand between an OD pair
@@ -927,18 +921,10 @@ def get_legacy_name():
 
 class SpecialEvent:
 
-    def __init__(self, name, beg_iteration, end_iteration) -> None:
+    def __init__(self, name) -> None:
         self.name = name
-        self.beg_iter = beg_iteration
-        self.end_iter = end_iteration
         self.affected_links = {}
 
-    def get_beg_iteration(self):
-        return self.beg_iter
-
-    def get_end_iteration(self):
-        return self.end_iter
-
 
 class DemandPeriod:
 
@@ -1031,6 +1017,7 @@ def __init__(self, id, alpha=0.15, beta=4, mu=1000,
         self.phf = phf
         self.avg_travel_time = 0
         self.voc = 0
+        self.reduction_ratio = 1
 
     def get_avg_travel_time(self):
         return self.avg_travel_time
@@ -1041,9 +1028,9 @@ def get_voc(self):
     def get_fftt(self):
         return self.fftt
 
-    def run_bpr(self, vol, reduction_ratio=1):
+    def run_bpr(self, vol):
         vol = max(0, vol)
-        self.voc = vol / max(SMALL_DIVISOR, self.capacity * reduction_ratio)
+        self.voc = vol / max(SMALL_DIVISOR, self.capacity * self.reduction_ratio)
         self.avg_travel_time = (
             self.fftt
             + self.fftt

path4gmns/colgen.py

@@ -23,12 +23,12 @@ def _update_link_cost_array(spnetworks):
             )
 
 
-def _update_link_travel_time(links, demand_periods=None):
+def _update_link_travel_time(links):
     for link in links:
         if link.length == 0:
             break
 
-        link.calculate_td_vdf(demand_periods)
+        link.calculate_td_vdf()
 
 
 def _update_link_and_column_volume(column_pool, links, iter_num, reduce_path_vol = True):
@@ -277,7 +277,6 @@ def perform_column_generation(column_gen_num, column_update_num, ui):
 
     links = A.get_links()
     ats = A.get_agent_types()
-    dps = A.get_demand_periods()
     column_pool = A.get_column_pool()
 
     st = time()
@@ -286,7 +285,7 @@ def perform_column_generation(column_gen_num, column_update_num, ui):
         print(f'current iteration number in column generation: {i}')
 
         _update_link_and_column_volume(column_pool, links, i)
-        _update_link_travel_time(links, dps)
+        _update_link_travel_time(links)
         # update generalized link cost before assignment
         _update_link_cost_array(A.get_spnetworks())
         # loop through all centroids on the base network
@@ -295,13 +294,11 @@ def perform_column_generation(column_gen_num, column_update_num, ui):
     print(f'\nprocessing time of generating columns: {time()-st:.2f} s\n')
 
     for i in range(column_update_num):
-        _update_link_and_column_volume(column_pool, links, i, False)
-        _update_link_travel_time(links)
         _update_column_gradient_cost_and_flow(column_pool, links, ats, i)
+        _update_link_and_column_volume(column_pool, links, i + 1, False)
+        _update_link_travel_time(links)
 
     # postprocessing
-    _update_link_and_column_volume(column_pool, links, column_gen_num, False)
-    _update_link_travel_time(links)
     _update_column_attributes(column_pool, links)
 
 

path4gmns/utils.py

@@ -830,15 +830,16 @@ def read_settings(input_dir, assignment):
                         raise KeyError
 
                     name = s['name']
-                    beg_iter = s['beg_iteration']
-                    end_iter = s['end_iteration']
-                    se = SpecialEvent(name, beg_iter, end_iter)
+                    se = SpecialEvent(name)
 
                     links = s['affected_links']
                     for link in links:
                         link_id = str(link['link_id'])
                         ratio = link['reduction_ratio']
                         se.affected_links[link_id] = ratio
+                        link_no = assignment.get_link_seq_no(link_id)
+                        link_obj = assignment.get_link(link_no)
+                        link_obj.set_reduction_ratio(i, ratio)
 
                     dp.special_event = se
                 except KeyError: