Switch sugarscape to using property layers (#2546)

mesa/examples/advanced/sugarscape_g1mt/agents.py

@@ -1,6 +1,6 @@
 import math
 
-from mesa.experimental.cell_space import CellAgent, FixedAgent
+from mesa.experimental.cell_space import CellAgent
 
 
 # Helper function
@@ -18,31 +18,6 @@ def get_distance(cell_1, cell_2):
     return math.sqrt(dx**2 + dy**2)
 
 
-class Resource(FixedAgent):
-    """
-    Resource:
-    - contains an amount of sugar and spice
-    - grows 1 amount of sugar at each turn
-    - grows 1 amount of spice at each turn
-    """
-
-    def __init__(self, model, max_sugar, max_spice, cell):
-        super().__init__(model)
-        self.sugar_amount = max_sugar
-        self.max_sugar = max_sugar
-        self.spice_amount = max_spice
-        self.max_spice = max_spice
-        self.cell = cell
-
-    def step(self):
-        """
-        Growth function, adds one unit of sugar and spice each step up to
-        max amount
-        """
-        self.sugar_amount = min([self.max_sugar, self.sugar_amount + 1])
-        self.spice_amount = min([self.max_spice, self.spice_amount + 1])
-
-
 class Trader(CellAgent):
     """
     Trader:
@@ -70,12 +45,6 @@ def __init__(
         self.prices = []
         self.trade_partners = []
 
-    def get_resource(self, cell):
-        for agent in cell.agents:
-            if isinstance(agent, Resource):
-                return agent
-        raise Exception(f"Resource agent not found in the position {cell.coordinate}")
-
     def get_trader(self, cell):
         """
         helper function used in self.trade_with_neighbors()
@@ -85,17 +54,6 @@ def get_trader(self, cell):
             if isinstance(agent, Trader):
                 return agent
 
-    def is_occupied_by_other(self, cell):
-        """
-        helper function part 1 of self.move()
-        """
-
-        if cell is self.cell:
-            # agent's position is considered unoccupied as agent can stay there
-            return False
-        # get contents of each cell in neighborhood
-        return any(isinstance(a, Trader) for a in cell.agents)
-
     def calculate_welfare(self, sugar, spice):
         """
         helper function
@@ -264,15 +222,15 @@ def move(self):
         neighboring_cells = [
             cell
             for cell in self.cell.get_neighborhood(self.vision, include_center=True)
-            if not self.is_occupied_by_other(cell)
+            if cell.is_empty
         ]
 
         # 2. determine which move maximizes welfare
 
         welfares = [
             self.calculate_welfare(
-                self.sugar + self.get_resource(cell).sugar_amount,
-                self.spice + self.get_resource(cell).spice_amount,
+                self.sugar + cell.sugar,
+                self.spice + cell.spice,
             )
             for cell in neighboring_cells
         ]
@@ -282,6 +240,7 @@ def move(self):
         # find the highest welfare in welfares
         max_welfare = max(welfares)
         # get the index of max welfare cells
+        # fixme: rewrite using enumerate and single loop
         candidate_indices = [
             i for i in range(len(welfares)) if math.isclose(welfares[i], max_welfare)
         ]
@@ -296,19 +255,17 @@ def move(self):
             for cell in candidates
             if math.isclose(get_distance(self.cell, cell), min_dist, rel_tol=1e-02)
         ]
+
         # 4. Move Agent
         self.cell = self.random.choice(final_candidates)
 
     def eat(self):
-        patch = self.get_resource(self.cell)
-        if patch.sugar_amount > 0:
-            self.sugar += patch.sugar_amount
-            patch.sugar_amount = 0
+        self.sugar += self.cell.sugar
+        self.cell.sugar = 0
         self.sugar -= self.metabolism_sugar
 
-        if patch.spice_amount > 0:
-            self.spice += patch.spice_amount
-            patch.spice_amount = 0
+        self.spice += self.cell.spice
+        self.cell.spice = 0
         self.spice -= self.metabolism_spice
 
     def maybe_die(self):
@@ -327,18 +284,8 @@ def trade_with_neighbors(self):
         2- trade (2 sessions)
         3- collect data
         """
-
-        neighbor_agents = [
-            self.get_trader(cell)
-            for cell in self.cell.get_neighborhood(radius=self.vision)
-            if self.is_occupied_by_other(cell)
-        ]
-
-        if len(neighbor_agents) == 0:
-            return
-
-            # iterate through traders in neighboring cells and trade
-        for a in neighbor_agents:
+        # iterate through traders in neighboring cells and trade
+        for a in self.cell.get_neighborhood(radius=self.vision).agents:
             self.trade(a)
 
         return

mesa/examples/advanced/sugarscape_g1mt/app.py

@@ -1,33 +1,27 @@
+import os
+import sys
+
+sys.path.insert(0, os.path.abspath("../../../.."))
+
+
 import numpy as np
 import solara
 from matplotlib.figure import Figure
 
-from mesa.examples.advanced.sugarscape_g1mt.agents import Trader
 from mesa.examples.advanced.sugarscape_g1mt.model import SugarscapeG1mt
 from mesa.visualization import Slider, SolaraViz, make_plot_component
 
 
 def SpaceDrawer(model):
     def portray(g):
         layers = {
-            "sugar": [[np.nan for j in range(g.height)] for i in range(g.width)],
-            "spice": [[np.nan for j in range(g.height)] for i in range(g.width)],
             "trader": {"x": [], "y": [], "c": "tab:red", "marker": "o", "s": 10},
         }
 
         for agent in g.all_cells.agents:
             i, j = agent.cell.coordinate
-            if isinstance(agent, Trader):
-                layers["trader"]["x"].append(i)
-                layers["trader"]["y"].append(j)
-            else:
-                # Don't visualize resource with value <= 1.
-                layers["sugar"][i][j] = (
-                    agent.sugar_amount if agent.sugar_amount > 1 else np.nan
-                )
-                layers["spice"][i][j] = (
-                    agent.spice_amount if agent.spice_amount > 1 else np.nan
-                )
+            layers["trader"]["x"].append(i)
+            layers["trader"]["y"].append(j)
         return layers
 
     fig = Figure()
@@ -36,10 +30,18 @@ def portray(g):
     # Sugar
     # Important note: imshow by default draws from upper left. You have to
     # always explicitly specify origin="lower".
-    im = ax.imshow(out["sugar"], cmap="spring", origin="lower")
+    im = ax.imshow(
+        np.ma.masked_where(model.grid.sugar.data <= 1, model.grid.sugar.data),
+        cmap="spring",
+        origin="lower",
+    )
     fig.colorbar(im, orientation="vertical")
     # Spice
-    ax.imshow(out["spice"], cmap="winter", origin="lower")
+    ax.imshow(
+        np.ma.masked_where(model.grid.spice.data <= 1, model.grid.spice.data),
+        cmap="winter",
+        origin="lower",
+    )
     # Trader
     ax.scatter(**out["trader"])
     ax.set_axis_off()
@@ -75,7 +77,11 @@ def portray(g):
 
 page = SolaraViz(
     model,
-    components=[SpaceDrawer, make_plot_component(["Trader", "Price"])],
+    components=[
+        SpaceDrawer,
+        make_plot_component("#Traders"),
+        make_plot_component("Price"),
+    ],
     model_params=model_params,
     name="Sugarscape {G1, M, T}",
     play_interval=150,

mesa/examples/advanced/sugarscape_g1mt/model.py

@@ -3,8 +3,9 @@
 import numpy as np
 
 import mesa
-from mesa.examples.advanced.sugarscape_g1mt.agents import Resource, Trader
+from mesa.examples.advanced.sugarscape_g1mt.agents import Trader
 from mesa.experimental.cell_space import OrthogonalVonNeumannGrid
+from mesa.experimental.cell_space.property_layer import PropertyLayer
 
 
 # Helper Functions
@@ -58,8 +59,8 @@ def __init__(
         # Initiate width and height of sugarscape
         self.width = width
         self.height = height
-        # Initiate population attributes
 
+        # Initiate population attributes
         self.enable_trade = enable_trade
         self.running = True
 
@@ -70,25 +71,25 @@ def __init__(
         # initiate datacollector
         self.datacollector = mesa.DataCollector(
             model_reporters={
-                "Trader": lambda m: len(m.agents_by_type[Trader]),
-                "Trade Volume": lambda m: sum(
-                    len(a.trade_partners) for a in m.agents_by_type[Trader]
-                ),
+                "#Traders": lambda m: len(m.agents),
+                "Trade Volume": lambda m: sum(len(a.trade_partners) for a in m.agents),
                 "Price": lambda m: geometric_mean(
-                    flatten([a.prices for a in m.agents_by_type[Trader]])
+                    flatten([a.prices for a in m.agents])
                 ),
             },
             agent_reporters={"Trade Network": lambda a: get_trade(a)},
         )
 
-        # read in landscape file from supplmentary material
-        sugar_distribution = np.genfromtxt(Path(__file__).parent / "sugar-map.txt")
-        spice_distribution = np.flip(sugar_distribution, 1)
+        # read in landscape file from supplementary material
+        self.sugar_distribution = np.genfromtxt(Path(__file__).parent / "sugar-map.txt")
+        self.spice_distribution = np.flip(self.sugar_distribution, 1)
 
-        for cell in self.grid.all_cells:
-            max_sugar = sugar_distribution[cell.coordinate]
-            max_spice = spice_distribution[cell.coordinate]
-            Resource(self, max_sugar, max_spice, cell)
+        self.grid.add_property_layer(
+            PropertyLayer.from_data("sugar", self.sugar_distribution)
+        )
+        self.grid.add_property_layer(
+            PropertyLayer.from_data("spice", self.spice_distribution)
+        )
 
         Trader.create_agents(
             self,
@@ -117,7 +118,12 @@ def step(self):
         and then randomly activates traders
         """
         # step Resource agents
-        self.agents_by_type[Resource].do("step")
+        self.grid.sugar.data = np.minimum(
+            self.grid.sugar.data + 1, self.sugar_distribution
+        )
+        self.grid.spice.data = np.minimum(
+            self.grid.spice.data + 1, self.spice_distribution
+        )
 
         # step trader agents
         # to account for agent death and removal we need a separate data structure to
@@ -142,6 +148,8 @@ def step(self):
             agent.trade_with_neighbors()
 
         # collect model level data
+        # fixme we can already collect agent class data
+        # fixme, we don't have resource agents anymore so this can be done simpler
         self.datacollector.collect(self)
         """
         Mesa is working on updating datacollector agent reporter