Bug fixes and additions to Epstein Civil Violence (#42)

* Bug fixes and additions to Epstein Civil Violence

This update changes a small set of bugs that was causing the model to
not exhibit the cyclical explosions of active agents seen in the
original Epstein paper. It also adds some small functionality
to the browser display, introducing sliders to allow the user
to change model parameters on the fly, and watch a graph
of agent state numbers.

Bug Fixes
- Fix agent state logic
- Fix Moore vs Von Neuman neighborhood selection to use
    Epstein paper behavior
- Fix agent vision bug (was 1 and not parameter `vision` when
    calculating neighborhood, which also fixes agent movement issue)
- Fix arrestee state issue (arrestee was not being reset to "Quiescent",
    and so was counting as "Active" for all nearby agents)

Additions and Changes
- Change display of agents where jailed agents are represented by grey
    square box
- Added sliders for model attributes

Co-authored-by: rht <rhtbot@protonmail.com>

Author: JoeHelbing

examples/epstein_civil_violence/epstein_civil_violence/agent.py

@@ -78,14 +78,9 @@ def step(self):
         self.update_neighbors()
         self.update_estimated_arrest_probability()
         net_risk = self.risk_aversion * self.arrest_probability
-        if (
-            self.condition == "Quiescent"
-            and (self.grievance - net_risk) > self.threshold
-        ):
+        if self.grievance - net_risk > self.threshold:
             self.condition = "Active"
-        elif (
-            self.condition == "Active" and (self.grievance - net_risk) <= self.threshold
-        ):
+        else:
             self.condition = "Quiescent"
         if self.model.movement and self.empty_neighbors:
             new_pos = self.random.choice(self.empty_neighbors)
@@ -96,7 +91,7 @@ def update_neighbors(self):
         Look around and see who my neighbors are
         """
         self.neighborhood = self.model.grid.get_neighborhood(
-            self.pos, moore=False, radius=1
+            self.pos, moore=True, radius=self.vision
         )
         self.neighbors = self.model.grid.get_cell_list_contents(self.neighborhood)
         self.empty_neighbors = [
@@ -167,6 +162,7 @@ def step(self):
             arrestee = self.random.choice(active_neighbors)
             sentence = self.random.randint(0, self.model.max_jail_term)
             arrestee.jail_sentence = sentence
+            arrestee.condition = "Quiescent"
         if self.model.movement and self.empty_neighbors:
             new_pos = self.random.choice(self.empty_neighbors)
             self.model.grid.move_agent(self, new_pos)
@@ -176,7 +172,7 @@ def update_neighbors(self):
         Look around and see who my neighbors are.
         """
         self.neighborhood = self.model.grid.get_neighborhood(
-            self.pos, moore=False, radius=1
+            self.pos, moore=True, radius=self.vision
         )
         self.neighbors = self.model.grid.get_cell_list_contents(self.neighborhood)
         self.empty_neighbors = [

examples/epstein_civil_violence/epstein_civil_violence/model.py

@@ -60,10 +60,12 @@ def __init__(
         self.iteration = 0
         self.schedule = mesa.time.RandomActivation(self)
         self.grid = mesa.space.SingleGrid(width, height, torus=True)
+
         model_reporters = {
             "Quiescent": lambda m: self.count_type_citizens(m, "Quiescent"),
             "Active": lambda m: self.count_type_citizens(m, "Active"),
             "Jailed": self.count_jailed,
+            "Cops": self.count_cops,
         }
         agent_reporters = {
             "x": lambda a: a.pos[0],
@@ -123,7 +125,7 @@ def count_type_citizens(model, condition, exclude_jailed=True):
         for agent in model.schedule.agents:
             if agent.breed == "cop":
                 continue
-            if exclude_jailed and agent.jail_sentence:
+            if exclude_jailed and agent.jail_sentence > 0:
                 continue
             if agent.condition == condition:
                 count += 1
@@ -136,6 +138,6 @@ def count_jailed(model):
         """
         count = 0
         for agent in model.schedule.agents:
-            if agent.breed == "citizen" and agent.jail_sentence:
+            if agent.breed == "citizen" and agent.jail_sentence > 0:
                 count += 1
         return count

examples/epstein_civil_violence/epstein_civil_violence/server.py

@@ -4,9 +4,10 @@
 from .model import EpsteinCivilViolence
 
 COP_COLOR = "#000000"
-AGENT_QUIET_COLOR = "#0066CC"
-AGENT_REBEL_COLOR = "#CC0000"
-JAIL_COLOR = "#757575"
+AGENT_QUIET_COLOR = "#648FFF"
+AGENT_REBEL_COLOR = "#FE6100"
+JAIL_COLOR = "#808080"
+JAIL_SHAPE = "rect"
 
 
 def citizen_cop_portrayal(agent):
@@ -25,29 +26,56 @@ def citizen_cop_portrayal(agent):
             AGENT_QUIET_COLOR if agent.condition == "Quiescent" else AGENT_REBEL_COLOR
         )
         color = JAIL_COLOR if agent.jail_sentence else color
+        shape = JAIL_SHAPE if agent.jail_sentence else "circle"
         portrayal["Color"] = color
-        portrayal["r"] = 0.8
+        portrayal["Shape"] = shape
+        if shape == "rect":
+            portrayal["w"] = 0.9
+            portrayal["h"] = 0.9
+        else:
+            portrayal["r"] = 0.5
+            portrayal["Filled"] = "false"
         portrayal["Layer"] = 0
 
     elif type(agent) is Cop:
         portrayal["Color"] = COP_COLOR
-        portrayal["r"] = 0.5
+        portrayal["r"] = 0.9
         portrayal["Layer"] = 1
+
     return portrayal
 
 
 model_params = {
     "height": 40,
     "width": 40,
-    "citizen_density": 0.7,
-    "cop_density": 0.074,
-    "citizen_vision": 7,
-    "cop_vision": 7,
-    "legitimacy": 0.8,
-    "max_jail_term": 1000,
+    "citizen_density": mesa.visualization.Slider(
+        "Initial Agent Density", 0.7, 0.0, 0.9, 0.1
+    ),
+    "cop_density": mesa.visualization.Slider(
+        "Initial Cop Density", 0.04, 0.0, 0.1, 0.01
+    ),
+    "citizen_vision": mesa.visualization.Slider("Citizen Vision", 7, 1, 10, 1),
+    "cop_vision": mesa.visualization.Slider("Cop Vision", 7, 1, 10, 1),
+    "legitimacy": mesa.visualization.Slider(
+        "Government Legitimacy", 0.82, 0.0, 1, 0.01
+    ),
+    "max_jail_term": mesa.visualization.Slider("Max Jail Term", 30, 0, 50, 1),
 }
-
 canvas_element = mesa.visualization.CanvasGrid(citizen_cop_portrayal, 40, 40, 480, 480)
+chart = mesa.visualization.ChartModule(
+    [
+        {"Label": "Quiescent", "Color": "#648FFF"},
+        {"Label": "Active", "Color": "#FE6100"},
+        {"Label": "Jailed", "Color": "#808080"},
+    ],
+    data_collector_name="datacollector",
+)
 server = mesa.visualization.ModularServer(
-    EpsteinCivilViolence, [canvas_element], "Epstein Civil Violence", model_params
+    EpsteinCivilViolence,
+    [
+        canvas_element,
+        chart,
+    ],
+    "Epstein Civil Violence",
+    model_params,
 )