Fix bug in tutorial to calculate MRS with potential trade

- update maybe_sell_spice() so calculate_MRS() takes potential sugar and spice based on trade
- update calculate_MRS() with kwargs so it can take potential trade but defaults to agents sugar and spice
Update increases agent_reporter due to number of trades creating memory issues
- Update data collection so non-relevant data rmeoved on each step (i.e. sugar and spice agents don't have trade partners)

examples/sugarscape_g1mt/sugarscape_g1mt/model.py

@@ -187,6 +187,13 @@ def step(self):
 
         # collect model level data
         self.datacollector.collect(self)
+        # Need to remove excess data
+        # Create local variable to store trade data
+        agent_trades = self.datacollector._agent_records[self.schedule.steps]
+        # Get rid of all None to reduce data storage needs
+        agent_trades = [agent for agent in agent_trades if agent[2] is not None]
+        # Reassign the dictionary value with lean trade data
+        self.datacollector._agent_records[self.schedule.steps] = agent_trades
 
     def run_model(self, step_count=1000):
         for i in range(step_count):

examples/sugarscape_g1mt/sugarscape_g1mt/trader_agents.py

@@ -140,16 +140,21 @@ def is_starved(self):
 
         return (self.sugar <= 0) or (self.spice <= 0)
 
-    def calculate_MRS(self):
-        """
-        Helper function for self.trade()
-
-        Determines what trader agent is needs and can give up
-        """
-
-        return (self.spice / self.metabolism_spice) / (
-            self.sugar / self.metabolism_sugar
-        )
+    def calculate_MRS(self, sugar= None, spice = None):
+        '''
+        Helper function for
+          - self.trade()
+          - self.maybe_self_spice()
+
+        Determines what trader agent needs and can give up
+        '''
+        if sugar == None:
+          sugar = self.sugar
+        if spice == None:
+          spice = self.spice
+
+        return (spice/self.metabolism_spice) / (
+                sugar/self.metabolism_sugar)
 
     def calculate_sell_spice_amount(self, price):
         """
@@ -205,8 +210,8 @@ def maybe_sell_spice(self, other, price, welfare_self, welfare_other):
             welfare_self < self.calculate_welfare(self_sugar, self_spice)
         ) and (welfare_other < other.calculate_welfare(other_sugar, other_spice))
 
-        # trade criteria #2 is their mrs crossing
-        mrs_not_crossing = self.calculate_MRS() > other.calculate_MRS()
+        #trade criteria #2 is their mrs crossing with potential trade
+        mrs_not_crossing = self.calculate_MRS(self_sugar, self_spice) > other.calculate_MRS(other_sugar, other_spice)
 
         if not (both_agents_better_off and mrs_not_crossing):
             return False