Resource restriction on part of the network#
In this notebook, we set up a basic simulation where two vessels move over a 1D network path consisting of three edges. We add a resrouce restriction on the middle edge: only one vessel can use that edge at a time. The second vessel now has to wait until the first vessel has passed the middle edge.
0. Import libraries#
# package(s) used for creating and geo-locating the graph
import networkx as nx
from pyproj import Geod
from shapely.geometry import Point
# package(s) related to the simulation (creating the vessel, running the simulation)
import datetime
import simpy
import opentnsim
from opentnsim.core.logutils import logbook2eventtable
from opentnsim.core.plotutils import generate_vessel_gantt_chart
# package(s) needed for inspecting the output
import pandas as pd
print("This notebook is executed with OpenTNSim version {}".format(opentnsim.__version__))
This notebook is executed with OpenTNSim version 1.3.7
1. Define object classes#
# make your preferred Vessel class out of available mix-ins.
Vessel = type(
"Vessel",
(
opentnsim.core.Identifiable, # allows to give the object a name and a random ID,
opentnsim.core.Movable, # allows the object to move, with a fixed speed, while logging this activity
),
{}
)
2. Create graph#
Next we create a network (a graph) along which the vessel can move. For this case we create a three edge network: a starting edge of 10 km long, a middle edge of 5 km long and an final edge of 10 km long.
# initialize geodetic calculator with WGS84 ellipsoid
geod = Geod(ellps="WGS84")
# starting point (longitude, latitude)
lon0, lat0 = 0, 0
# compute the other point 100 km East from Point 0
lon1, lat1, _ = geod.fwd(lon0, lat0, 90, 10000) # East from Point 0
lon2, lat2, _ = geod.fwd(lon1, lat1, 90, 5000) # East from Point 1
lon3, lat3, _ = geod.fwd(lon2, lat2, 90, 10000) # East from Point 2
# define nodes with their geographic coordinates
coords = {
"0": (lon0, lat0),
"1": (lon1, lat1),
"2": (lon2, lat2),
"3": (lon3, lat3),
}
# create list of edges
edges = [
("0", "1"), ("1", "0"),
("1", "2"), ("2", "1"),
("2", "3"), ("3", "2"),
] # bi-directional edge
# create a directed graph
FG = nx.DiGraph()
# add nodes
for name, coord in coords.items():
FG.add_node(name, geometry=Point(coord[0], coord[1]))
# add edges
for edge in edges:
FG.add_edge(edge[0], edge[1], weight=1)
opentnsim.graph.plot_graph(FG)
3. Run simulation#
def mission(env, vessel):
"""
Method that defines the mission of the vessel.
In this case:
keep moving along the path until its end point is reached
"""
while True:
yield from vessel.move()
if vessel.geometry == nx.get_node_attributes(env.graph, "geometry")[vessel.route[-1]]:
break
# start simpy environment
simulation_start = datetime.datetime(2024, 1, 1, 0, 0, 0)
env = simpy.Environment(initial_time=simulation_start.timestamp())
env.epoch = simulation_start
# add sites to graph
FG.edges[('1', '2')]["Resources"] = simpy.Resource(env, 1)
# add graph to environment
env.graph = FG
# create vessel from dict
data_vessel = {
"env": env, # needed for simpy simulation, left empty for now
"name": "Vessel", # required by Identifiable
"geometry": env.graph.nodes['0']['geometry'], # required by Locatable, left empty for now
"route": nx.dijkstra_path(env.graph, "0", "3"), # required by Routeable, left empty for now
"v": 1, # required by Movable, 1 m/s to check if the distance is covered in the expected time
}
vessel_1 = Vessel(**data_vessel)
vessel_1.name = 'Vessel 1'
vessel_2 = Vessel(**data_vessel)
vessel_2.name = 'Vessel 2'
# start the simulation
env.process(mission(env, vessel_1))
env.process(mission(env, vessel_2))
env.run()
4. Inspect output#
We can now inspect the simulation output by inspecting the vessel.logbook. Note that the Log mix-in was included when we added Movable. The vessel.logbook keeps track of the moving activities of the vessel. For each discrete event OpenTNSim logs an event message, the start/stop time and the location. The vessel.logbook is of type dict. For convenient inspection it can be loaded into a Pandas dataframe.
# load the logbook data into a dataframe
df = pd.DataFrame.from_dict(vessel_1.logbook)
print("'{}' logbook data:".format(vessel_1.name))
print('')
display(df)
'Vessel 1' logbook data:
| Message | Timestamp | Value | Geometry | |
|---|---|---|---|---|
| 0 | Sailing from node 0 to node 1 start | 2024-01-01 00:00:00 | 0.0 | POINT (0 0) |
| 1 | Sailing from node 0 to node 1 stop | 2024-01-01 02:46:40 | 10000.0 | POINT (0.0898315284119522 0) |
| 2 | Sailing from node 1 to node 2 start | 2024-01-01 02:46:40 | 10000.0 | POINT (0.0898315284119522 0) |
| 3 | Sailing from node 1 to node 2 stop | 2024-01-01 04:10:00 | 15000.0 | POINT (0.1347472926179282 0) |
| 4 | Sailing from node 2 to node 3 start | 2024-01-01 04:10:00 | 15000.0 | POINT (0.1347472926179282 0) |
| 5 | Sailing from node 2 to node 3 stop | 2024-01-01 06:56:40 | 25000.0 | POINT (0.2245788210298804 0) |
# load the logbook data into a dataframe
df = pd.DataFrame.from_dict(vessel_2.logbook)
print("'{}' logbook data:".format(vessel_2.name))
print('')
display(df)
'Vessel 2' logbook data:
| Message | Timestamp | Value | Geometry | |
|---|---|---|---|---|
| 0 | Sailing from node 0 to node 1 start | 2024-01-01 00:00:00 | 0.0 | POINT (0 0) |
| 1 | Sailing from node 0 to node 1 stop | 2024-01-01 02:46:40 | 10000.0 | POINT (0.0898315284119522 0) |
| 2 | Waiting to pass edge 1 - 2 start | 2024-01-01 02:46:40 | 10000.0 | POINT (0.0898315284119522 0) |
| 3 | Waiting to pass edge 1 - 2 stop | 2024-01-01 04:10:00 | 10000.0 | POINT (0.0898315284119522 0) |
| 4 | Sailing from node 1 to node 2 start | 2024-01-01 04:10:00 | 10000.0 | POINT (0.0898315284119522 0) |
| 5 | Sailing from node 1 to node 2 stop | 2024-01-01 05:33:20 | 15000.0 | POINT (0.1347472926179282 0) |
| 6 | Sailing from node 2 to node 3 start | 2024-01-01 05:33:20 | 15000.0 | POINT (0.1347472926179282 0) |
| 7 | Sailing from node 2 to node 3 stop | 2024-01-01 08:20:00 | 25000.0 | POINT (0.2245788210298804 0) |
The inspection of the logbook data shows that Vessel moved from its origin (Node 0) to its destination (Node 1). The print statements show that the length of the route from Node 0 to Node 1 is exactly 100 km. At a given speed of 1 m/s the trip duration should be exactly 100000 seconds, as is indeed shown to be the case.
df_eventtable = logbook2eventtable([vessel_1, vessel_2])
df_eventtable
| object id | object name | activity name | start location | stop location | start time | stop time | distance (m) | duration (s) | |
|---|---|---|---|---|---|---|---|---|---|
| 0 | fa34dc42-cce6-44ff-9a52-645ee603b06d | Vessel 1 | Sailing from node 0 to node 1 | POINT (0 0) | POINT (0.0898315284119522 0) | 2024-01-01 00:00:00 | 2024-01-01 02:46:40 | 10000.0 | 10000.0 |
| 1 | fa34dc42-cce6-44ff-9a52-645ee603b06d | Vessel 1 | Sailing from node 1 to node 2 | POINT (0.0898315284119522 0) | POINT (0.1347472926179282 0) | 2024-01-01 02:46:40 | 2024-01-01 04:10:00 | 5000.0 | 5000.0 |
| 2 | fa34dc42-cce6-44ff-9a52-645ee603b06d | Vessel 1 | Sailing from node 2 to node 3 | POINT (0.1347472926179282 0) | POINT (0.2245788210298804 0) | 2024-01-01 04:10:00 | 2024-01-01 06:56:40 | 10000.0 | 10000.0 |
| 3 | 206d2945-390c-4487-bf0c-acb9ba4f2c2b | Vessel 2 | Sailing from node 0 to node 1 | POINT (0 0) | POINT (0.0898315284119522 0) | 2024-01-01 00:00:00 | 2024-01-01 02:46:40 | 10000.0 | 10000.0 |
| 4 | 206d2945-390c-4487-bf0c-acb9ba4f2c2b | Vessel 2 | Waiting to pass edge 1 - 2 | POINT (0.0898315284119522 0) | POINT (0.0898315284119522 0) | 2024-01-01 02:46:40 | 2024-01-01 04:10:00 | 0.0 | 5000.0 |
| 5 | 206d2945-390c-4487-bf0c-acb9ba4f2c2b | Vessel 2 | Sailing from node 1 to node 2 | POINT (0.0898315284119522 0) | POINT (0.1347472926179282 0) | 2024-01-01 04:10:00 | 2024-01-01 05:33:20 | 5000.0 | 5000.0 |
| 6 | 206d2945-390c-4487-bf0c-acb9ba4f2c2b | Vessel 2 | Sailing from node 2 to node 3 | POINT (0.1347472926179282 0) | POINT (0.2245788210298804 0) | 2024-01-01 05:33:20 | 2024-01-01 08:20:00 | 10000.0 | 10000.0 |
generate_vessel_gantt_chart(df_eventtable)
The inspection of the logbook data shows that the mission of the Vessel, resulted in four cycles where loading - sailing - unloading - sailing were executed in a sequence. The sites had a capacity of 100, and the Vessel a capacity of 30. It can be seen that the last cycle the loading and unloading take less time because the Vessel sailed only partially filled.