JSON - MikeLydeamore/JCompSim GitHub Wiki

For 'simple' models, it is possible to represent the state-transition system using two JSON files which can be directly inputted into the simulator without changing any code. Two JSON files are required: one representing the states and one representing the transitions.

States

The states JSON lists each state of the model and it's initial value. An example:

{
   "S": 90,
   "I": 10,
   "R": 0
}

This defines 3 states: S, I and R with initial values 90, 10 and 0 respectively.

Transitions

The transitions JSON is slightly more involved. All types of transitions require:

• source_state,
• destination_state,
• parameter.

Additionally, one must specify the type of transition. The following type of transitions are available:

• Individual:
  Specify "transition_type": "individual"
  Rate will be of the form parameter * source_state.

• Mass Action:
  Specify "transition_type": "mass-action"
  Optional "governing_states": ["list", "of", "states"]
  Rate will be of the form parameter * source_state * sum(governing_states).

• Constant:
  Specify "transition_type": "constant"
  Rate will be of the form parameter * Indicator(source_state > 0).

Example

For the SIR model, the following transitions JSON is used:

[
{
	"source_state": "S",
	"destination_state": "I",
	"parameter": 0.018,
	"transition_type": "mass-action",
	"governing_states": ["I"]
},
{
	"source_state": "I",
	"destination_state": "R",
	"parameter": 1,
	"transition_type": "individual"
}
]

More examples are available inside the repository's Models directory.