Stopped subclassing Agent just for the sake of defining an agent program.

darius · darius · commit 581beb828508 · 2011-10-17T07:42:13.000Z
diff --git a/agents.py b/agents.py
@@ -99,53 +99,44 @@ def new_program(percept):
 
 #______________________________________________________________________________
 
-class TableDrivenAgent(Agent):
+def TableDrivenAgentProgram(table):
     """This agent selects an action based on the percept sequence.
     It is practical only for tiny domains.
-    To customize it you provide a table to the constructor. [Fig. 2.7]"""
-    
-    def __init__(self, table):
-        "Supply as table a dictionary of all {percept_sequence:action} pairs."
-        percepts = []
-        def program(percept):
-            percepts.append(percept)
-            action = table.get(tuple(percepts))
-            return action
-        Agent.__init__(self, program)
-
+    To customize it, provide as table a dictionary of all
+    {percept_sequence:action} pairs. [Fig. 2.7]"""
+    percepts = []
+    def program(percept):
+        percepts.append(percept)
+        action = table.get(tuple(percepts))
+        return action
+    return program
 
-class RandomAgent(Agent):
+def RandomAgentProgram(actions):
     "An agent that chooses an action at random, ignoring all percepts."
-
-    def __init__(self, actions):
-        def program(percept):
-            return random.choice(actions)
-        Agent.__init__(self, program)
+    def program(percept):
+        return random.choice(actions)
+    return program
 
 #______________________________________________________________________________
 
-class SimpleReflexAgent(Agent):
+def SimpleReflexAgentProgram(rules, interpret_input):
     "This agent takes action based solely on the percept. [Fig. 2.10]"
+    def program(percept):
+        state = interpret_input(percept)
+        rule = rule_match(state, rules)
+        action = rule.action
+        return action
+    return program
 
-    def __init__(self, rules, interpret_input):
-        def program(percept):
-            state = interpret_input(percept)
-            rule = rule_match(state, rules)
-            action = rule.action
-            return action
-        Agent.__init__(self, program)
-
-class ModelBasedReflexAgent(Agent):
+def ModelBasedReflexAgentProgram(rules, update_state):
     "This agent takes action based on the percept and state. [Fig. 2.12]"
-
-    def __init__(self, rules, update_state):
-        def program(percept):
-            program.state = update_state(program.state, program.action, percept)
-            rule = rule_match(program.state, rules)
-            action = rule.action
-            return action
-        program.state = program.action = None
-        Agent.__init__(self, program)
+    def program(percept):
+        program.state = update_state(program.state, program.action, percept)
+        rule = rule_match(program.state, rules)
+        action = rule.action
+        return action
+    program.state = program.action = None
+    return program
 
 def rule_match(state, rules):
     "Find the first rule that matches state."
@@ -157,20 +148,10 @@ def rule_match(state, rules):
 
 loc_A, loc_B = (0, 0), (1, 0) # The two locations for the Vacuum world
 
-class ReflexVacuumAgent(Agent):
-    "A reflex agent for the two-state vacuum environment. [Fig. 2.8]"
-
-    def __init__(self):
-        def program((location, status)):
-            if status == 'Dirty': return 'Suck'
-            elif location == loc_A: return 'Right'
-            elif location == loc_B: return 'Left'
-        Agent.__init__(self, program)
-
 
 def RandomVacuumAgent():
     "Randomly choose one of the actions from the vacuum environment."
-    return RandomAgent(['Right', 'Left', 'Suck', 'NoOp'])
+    return Agent(RandomAgentProgram(['Right', 'Left', 'Suck', 'NoOp']))
 
 
 def TableDrivenVacuumAgent():
@@ -186,22 +167,28 @@ def TableDrivenVacuumAgent():
              ((loc_A, 'Clean'), (loc_A, 'Clean'), (loc_A, 'Dirty')): 'Suck',
              # ...
              }
-    return TableDrivenAgent(table)
+    return Agent(TableDrivenAgentProgram(table))
 
 
-class ModelBasedVacuumAgent(Agent):
-    "An agent that keeps track of what locations are clean or dirty."
+def ReflexVacuumAgent():
+    "A reflex agent for the two-state vacuum environment. [Fig. 2.8]"
+    def program((location, status)):
+        if status == 'Dirty': return 'Suck'
+        elif location == loc_A: return 'Right'
+        elif location == loc_B: return 'Left'
+    return Agent(program)
 
-    def __init__(self):
-        model = {loc_A: None, loc_B: None}
-        def program((location, status)):
-            "Same as ReflexVacuumAgent, except if everything is clean, do NoOp."
-            model[location] = status ## Update the model here
-            if model[loc_A] == model[loc_B] == 'Clean': return 'NoOp'
-            elif status == 'Dirty': return 'Suck'
-            elif location == loc_A: return 'Right'
-            elif location == loc_B: return 'Left'
-        Agent.__init__(self, program)
+def ModelBasedVacuumAgent():
+    "An agent that keeps track of what locations are clean or dirty."
+    model = {loc_A: None, loc_B: None}
+    def program((location, status)):
+        "Same as ReflexVacuumAgent, except if everything is clean, do NoOp."
+        model[location] = status ## Update the model here
+        if model[loc_A] == model[loc_B] == 'Clean': return 'NoOp'
+        elif status == 'Dirty': return 'Suck'
+        elif location == loc_A: return 'Right'
+        elif location == loc_B: return 'Left'
+    return Agent(program)
 
 #______________________________________________________________________________
 
diff --git a/logic.py b/logic.py
@@ -93,17 +93,16 @@ def retract(self, sentence):
 
 #______________________________________________________________________________
     
-class KB_Agent(agents.Agent):
-    """A generic logical knowledge-based agent. [Fig. 7.1]"""
-    def __init__(self, KB):
-        steps = itertools.count()
-        def program(percept):
-            t = steps.next()
-            KB.tell(self.make_percept_sentence(percept, t))
-            action = KB.ask(self.make_action_query(t))[expr('action')]
-            KB.tell(self.make_action_sentence(action, t))
-            return action
-        agents.Agent.__init__(self, program)
+def KB_AgentProgram(KB):
+    """A generic logical knowledge-based agent program. [Fig. 7.1]"""
+    steps = itertools.count()
+
+    def program(percept):
+        t = steps.next()
+        KB.tell(make_percept_sentence(percept, t))
+        action = KB.ask(make_action_query(t))
+        KB.tell(make_action_sentence(action, t))
+        return action
 
     def make_percept_sentence(self, percept, t):
         return Expr("Percept")(percept, t)
@@ -112,7 +111,9 @@ def make_action_query(self, t):
         return expr("ShouldDo(action, %d)" % t)
 
     def make_action_sentence(self, action, t):
-        return Expr("Did")(action, t)
+        return Expr("Did")(action[expr('action')], t)
+
+    return program
 
 #______________________________________________________________________________
 
diff --git a/probability.py b/probability.py
@@ -3,22 +3,19 @@
 
 from utils import *
 from logic import extend
-import agents
 from random import random, seed
 
 #______________________________________________________________________________
 
-class DTAgent(agents.Agent):
+def DTAgentProgram(belief_state):
     "A decision-theoretic agent. [Fig. 13.1]"
-
-    def __init__(self, belief_state):
-        def program(percept):
-            belief_state.observe(program.action, percept)
-            program.action = argmax(belief_state.actions(), 
-                                    belief_state.expected_outcome_utility)
-            return program.action
-        program.action = None
-        agents.Agent.__init__(self, program)
+    def program(percept):
+        belief_state.observe(program.action, percept)
+        program.action = argmax(belief_state.actions(), 
+                                belief_state.expected_outcome_utility)
+        return program.action
+    program.action = None
+    return program
 
 #______________________________________________________________________________
 
diff --git a/search.py b/search.py
@@ -5,7 +5,6 @@
 functions."""
 
 from utils import *
-import agents
 import math, random, sys, time, bisect, string
 
 #______________________________________________________________________________
