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Forest Fire Model.ipynb

Forest Fire Model


The forest fire model is a simple, cellular automaton simulation of a fire spreading through a forest. The forest is a grid of cells, each of which can either be empty or contain a tree. Trees can be unburned, on fire, or burned. The fire spreads from every on-fire tree to unburned neighbors; the on-fire tree then becomes burned. This continues until the fire dies out.

How to Run

To run the model interactively, run mesa runserver in this directory. e.g.

    $ mesa runserver

Then open your browser to and press Reset, then Run.

To view and run the model analyses, use the Forest Fire Model Notebook.



This defines the model. There is one agent class, TreeCell. Each TreeCell object which has (x, y) coordinates on the grid, and its condition is Fine by default. Every step, if the tree's condition is On Fire, it spreads the fire to any Fine trees in its Von Neumann neighborhood before changing its own condition to Burned Out.

The ForestFire class is the model container. It is instantiated with width and height parameters which define the grid size, and density, which is the probability of any given cell having a tree in it. When a new model is instantiated, cells are randomly filled with trees with probability equal to density. All the trees in the left-hand column (x=0) are set to On Fire.

Each step of the model, trees are activated in random order, spreading the fire and burning out. This continues until there are no more trees on fire -- the fire has completely burned out.


This code defines and launches the in-browser visualization for the ForestFire model. It includes the forest_fire_draw method, which takes a TreeCell object as an argument and turns it into a portrayal to be drawn in the browser. Each tree is drawn as a rectangle filling the entire cell, with a color based on its condition. Fine trees are green, On Fire trees red, and Burned Out trees are black.

Further Reading

Read about the Forest Fire model on Wikipedia:

This is directly based on the comparable NetLogo model:

Wilensky, U. (1997). NetLogo Fire model. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL.

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