Ps-i 2.2 - fields

General description

A field is a collection of agents. Ps-i was designed to allow multiple fields. However due to time constraints the interface allowing interaction of agents from different fields was not implemented. Thus though one might have multiple field sections in the input file it is recommended only to have one. Also (again due to time constraints) only rectangular fields with square lattice were implemented. The design, though, allows for straightforward addition of other fields types - for example hexagonal lattice.

Section format

Example:

field 'landscape'
	dimensions 50 50

	paint 'basic' rect(1,1,48,48) 100
	paint 'basic' "rectangle(1,1,field_width-2,field_width-2)"
		with 'cache' "make_b_repertoire"
	paint 'entrepreneur' "rectangle(1,1,field_width-2,field_width-2) and (rand < e_ratio)"
		with 'cache' "make_e_repertoire"
	paint 'border' "rectangle(0,0,field_width-1,0)"
	paint 'border' "rectangle(0,field_width-1,field_width-1,field_width)"
	paint 'border' "rectangle(0,0,0,field_width-1)"
	paint 'border' "rectangle(field_width-1,0,field_width-1,field_width-1)"
end

There are four kind of directives:

paint directive - specifies the operation to perform when seeding fields. It takes two arguments: name of the agentclass to seed with, and boolean function, which is evaluated for each agent and, when false or zero precludes seeding of the agent.
with directive - must always follow paint directive or another with directive. It has two arguments: name of the attribute and function which value is assigned to the attribute when agent is seeded. This permits custom assignment of attributes when fields are reseeded.
dimentions directive - specifies the size of the field. It takes two arguments - width and height
agent directive - this one is used only in snapshots. It is never evaluated when loading as a model. Its syntax is implementation specific.

Note that coordinate system in the field are set up in such a way that the top left agent has coordinates (0,0) and bottom right has coordinates (field_width-1,field_height-1). Related See also About Ps-i 2.2, agentclass sections.