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soil/examples/events_and_messages/cars_sim.py
J. Fernando Sánchez feab0ba79e Large set of changes for v0.30
The examples weren't being properly tested in the last commit. When we fixed
that a lot of bugs in the new implementation of environment and agent were
found, which accounts for most of these changes.

The main difference is the mechanism to load simulations from a configuration
file. For that to work, we had to rework our module loading code in
`serialization` and add a `source_file` attribute to configurations (and
simulations, for that matter).
2023-04-14 19:41:24 +02:00

226 lines
7.9 KiB
Python

"""
This is an example of a simplified city, where there are Passengers and Drivers that can take those passengers
from their location to their desired location.
An example scenario could play like the following:
- Drivers start in the `wandering` state, where they wander around the city until they have been assigned a journey
- Passenger(1) tells every driver that it wants to request a Journey.
- Each driver receives the request.
If Driver(2) is interested in providing the Journey, it asks Passenger(1) to confirm that it accepts Driver(2)'s request
- When Passenger(1) accepts the request, two things happen:
- Passenger(1) changes its state to `driving_home`
- Driver(2) starts moving towards the origin of the Journey
- Once Driver(2) reaches the origin, it starts moving itself and Passenger(1) to the destination of the Journey
- When Driver(2) reaches the destination (carrying Passenger(1) along):
- Driver(2) starts wondering again
- Passenger(1) dies, and is removed from the simulation
- If there are no more passengers available in the simulation, Drivers die
"""
from __future__ import annotations
from typing import Optional
from soil import *
from soil import events
from mesa.space import MultiGrid
# More complex scenarios may use more than one type of message between objects.
# A common pattern is to use `enum.Enum` to represent state changes in a request.
@dataclass
class Journey:
"""
This represents a request for a journey. Passengers and drivers exchange this object.
A journey may have a driver assigned or not. If the driver has not been assigned, this
object is considered a "request for a journey".
"""
origin: (int, int)
destination: (int, int)
tip: float
passenger: Passenger
driver: Optional[Driver] = None
class City(EventedEnvironment):
"""
An environment with a grid where drivers and passengers will be placed.
The number of drivers and riders is configurable through its parameters:
:param str n_cars: The total number of drivers to add
:param str n_passengers: The number of passengers in the simulation
:param list agents: Specific agents to use in the simulation. It overrides the `n_passengers`
and `n_cars` params.
:param int height: Height of the internal grid
:param int width: Width of the internal grid
"""
n_cars = 1
n_passengers = 10
height = 100
width = 100
def init(self):
self.grid = MultiGrid(width=self.width, height=self.height, torus=False)
if not self.agents:
self.add_agents(Driver, k=self.n_cars)
self.add_agents(Passenger, k=self.n_passengers)
for agent in self.agents:
self.grid.place_agent(agent, (0, 0))
self.grid.move_to_empty(agent)
self.total_earnings = 0
self.add_model_reporter("total_earnings")
@report
@property
def number_passengers(self):
return self.count_agents(agent_class=Passenger)
class Driver(Evented, FSM):
pos = None
journey = None
earnings = 0
def on_receive(self, msg, sender):
"""This is not a state. It will run (and block) every time check_messages is invoked"""
if self.journey is None and isinstance(msg, Journey) and msg.driver is None:
msg.driver = self
self.journey = msg
def check_passengers(self):
"""If there are no more passengers, stop forever"""
c = self.count_agents(agent_class=Passenger)
self.info(f"Passengers left {c}")
if not c:
self.die()
@default_state
@state
def wandering(self):
"""Move around the city until a journey is accepted"""
target = None
self.check_passengers()
self.journey = None
while self.journey is None: # No potential journeys detected (see on_receive)
if target is None or not self.move_towards(target):
target = self.random.choice(
self.model.grid.get_neighborhood(self.pos, moore=False)
)
self.check_passengers()
# This will call on_receive behind the scenes, and the agent's status will be updated
self.check_messages()
yield Delta(30) # Wait at least 30 seconds before checking again
try:
# Re-send the journey to the passenger, to confirm that we have been selected
self.journey = yield self.journey.passenger.ask(self.journey, timeout=60)
except events.TimedOut:
# No journey has been accepted. Try again
self.journey = None
return
return self.driving
@state
def driving(self):
"""The journey has been accepted. Pick them up and take them to their destination"""
while self.move_towards(self.journey.origin):
yield
while self.move_towards(self.journey.destination, with_passenger=True):
yield
self.earnings += self.journey.tip
self.model.total_earnings += self.journey.tip
self.check_passengers()
return self.wandering
def move_towards(self, target, with_passenger=False):
"""Move one cell at a time towards a target"""
self.info(f"Moving { self.pos } -> { target }")
if target[0] == self.pos[0] and target[1] == self.pos[1]:
return False
next_pos = [self.pos[0], self.pos[1]]
for idx in [0, 1]:
if self.pos[idx] < target[idx]:
next_pos[idx] += 1
break
if self.pos[idx] > target[idx]:
next_pos[idx] -= 1
break
self.model.grid.move_agent(self, tuple(next_pos))
if with_passenger:
self.journey.passenger.pos = (
self.pos
) # This could be communicated through messages
return True
class Passenger(Evented, FSM):
pos = None
def on_receive(self, msg, sender):
"""This is not a state. It will be run synchronously every time `check_messages` is run"""
if isinstance(msg, Journey):
self.journey = msg
return msg
@default_state
@state
def asking(self):
destination = (
self.random.randint(0, self.model.grid.height),
self.random.randint(0, self.model.grid.width),
)
self.journey = None
journey = Journey(
origin=self.pos,
destination=destination,
tip=self.random.randint(10, 100),
passenger=self,
)
timeout = 60
expiration = self.now + timeout
self.model.broadcast(journey, ttl=timeout, sender=self, agent_class=Driver)
while not self.journey:
self.info(f"Passenger at: { self.pos }. Checking for responses.")
try:
# This will call check_messages behind the scenes, and the agent's status will be updated
# If you want to avoid that, you can call it with: check=False
yield self.received(expiration=expiration)
except events.TimedOut:
self.info(f"Passenger at: { self.pos }. Asking for journey.")
self.model.broadcast(
journey, ttl=timeout, sender=self, agent_class=Driver
)
expiration = self.now + timeout
return self.driving_home
@state
def driving_home(self):
while (
self.pos[0] != self.journey.destination[0]
or self.pos[1] != self.journey.destination[1]
):
try:
yield self.received(timeout=60)
except events.TimedOut:
pass
self.die("Got home safe!")
simulation = Simulation(name="RideHailing",
model=City,
seed="carsSeed",
max_time=1000,
model_params=dict(n_passengers=2))
if __name__ == "__main__":
simulation.run()