Getting Started

Installation

pip install unsim

If you want to use JAX acceleration, install your preferred JAX build such as jax[cpu] and jax[cuda13]. The optimal installation depends on your hardware and software configuration, so please check the JAX official document.

First simulation

Simple scenario in a Y-shaped merge network:

from unsim import World
import matplotlib.pyplot as plt

# Define the main simulation
# Units are standardized to seconds (s) and meters (m)
W = World(name="merge", deltat=5, tmax=1200,
          print_mode=1, save_mode=1, show_mode=1)

# Define the network
W.addNode("orig1", x=0, y=0)
W.addNode("orig2", x=0, y=2)
W.addNode("merge", x=1, y=1)
W.addNode("dest", x=2, y=1)
W.addLink("link1", "orig1", "merge", length=1000, free_flow_speed=20, capacity=0.8, merge_priority=1)
W.addLink("link2", "orig2", "merge", length=1000, free_flow_speed=20, capacity=0.8, merge_priority=1)
W.addLink("link3", "merge", "dest", length=1000, free_flow_speed=20)

# Define the vehicle demand
W.adddemand("orig1", "dest", t_start=0, t_end=1000, flow=0.45)
W.adddemand("orig2", "dest", t_start=400, t_end=1000, flow=0.6)

# Run the simulation
W.exec_simulation()

# Analysis
W.analyzer.print_simple_stats()

W.analyzer.network(t=200)
W.analyzer.network(t=800)
plt.show()

Expected results:

Simulation completed. merge
  Simulation Results:
    Total trips:     810.0
    Completed trips: 740.0
    Total travel time: 136825.0 s
    Avg travel time: 184.9 s
    Avg delay:       84.9 s

For further usage including Autodiff, please see the Tutorial.