10. Charts

This 10th step illustrates how to define charts.

Formulation

• Addition of a new display to visualize:
  • One chart representing the evolution of the quantity of prey and predator agents over time.
  • Two histograms representing the energy distribution of the prey and predator agents.

Model Definition

output

GAMA can display various chart types:

• Time series
• Pie charts
• Histograms

A chart must be defined in a display: it behaves exactly like any other layer.

Definition of a chart:

chart chart_name type: chart_type {
    [data]
}

The data to draw are defined inside the chart block as follow, using the data statement:

data data_legend value: data_value

We add a new display called Population_information that refreshes every 5 simulation steps. Inside this display, we define 3 charts: one of type series (i.e. time series chart), two of type histogram:

• "Species evolution"; background: white; size: {1, 0.5}; position: {0, 0}

  • data1: nb_preys; color : blue
  • data2: nb_predators; color : red

• "Prey Energy Distribution"; background: lightGray; size: {0.5, 0.5}; position: {0, 0.5}

  • data "]0;0.25]": number of preys with (each.energy <= 0.25) ;
  • data "]0.25;0.5]": number of preys with ((each.energy > 0.25) and (each.energy <= 0.5)) ;
  • data "]0.5;0.75]": number of preys with ((each.energy > 0.5) and (each.energy <= 0.75)) ;
  • data "]0.75;1]": number of preys with (each.energy > 0.75) ;

• "Predator Energy Distribution"; background: lightGray; size: {0.5, 0.5}; position: {0.5, 0.5}

  • data "]0;0.25]": number of predators with (each.energy <= 0.25) ;
  • data "]0.25;0.5]": number of predators with ((each.energy > 0.25) and (each.energy <= 0.5)) ;
  • data "]0.5;0.75]": number of predators with ((each.energy > 0.5) and (each.energy <= 0.75)) ;
  • data "]0.75;1]": number of predators with (each.energy > 0.75) ;

To evaluate the value of the data of the two histogram, we use the operator list count condition that returns the number of elements of list for which the condition is true.

display Population_information refresh:every(5#cycles) {
    chart "Species evolution" type: series size: {1,0.5} position: {0, 0} {
	data "number_of_preys" value: nb_preys color: #blue ;
	data "number_of_predator" value: nb_predators color: #red ;
    }
    chart "Prey Energy Distribution" type: histogram background: #lightgray size: {0.5,0.5} position: {0, 0.5} {
	data "]0;0.25]" value: prey count (each.energy <= 0.25) color:#blue;
	data "]0.25;0.5]" value: prey count ((each.energy > 0.25) and (each.energy <= 0.5)) color:#blue;
	data "]0.5;0.75]" value: prey count ((each.energy > 0.5) and (each.energy <= 0.75)) color:#blue;
	data "]0.75;1]" value: prey count (each.energy > 0.75) color:#blue;
    }
    chart "Predator Energy Distribution" type: histogram background: #lightgray size: {0.5,0.5} position: {0.5, 0.5} {
	data "]0;0.25]" value: predator count (each.energy <= 0.25) color: #red ;
	data "]0.25;0.5]" value: predator count ((each.energy > 0.25) and (each.energy <= 0.5)) color: #red ;
	data "]0.5;0.75]" value: predator count ((each.energy > 0.5) and (each.energy <= 0.75)) color: #red ;
	data "]0.75;1]" value: predator count (each.energy > 0.75) color: #red;
    }
}

Complete Model

https://github.com/gama-platform/gama.old/blob/GAMA_1.9.2/msi.gama.models/models/Tutorials/Predator%20Prey/models/Model%2010.gaml