`Opinion`: An opinion dynamics process

class epydemic.Opinion

Model for opinion spreading dynamics.

This model is based on the work of Moreno et alia [MNP04], in which a single rumour is spread using an epidemic-like process, with compartments consisting of those ignorant of the rumour (IGNORANT), those who have heard the rumour and can spread it (SPREADER), and those who have heard the rumour and now do not believe it (or at least do not spread it (STIFLER). The difference between this process and SIR is that “spreaders” become “stiflers” at a rate proportional to their contact with stiflers and spreaders.

Dynamical states

Opinion dynamics uses three compartments:

Opinion.IGNORANT: Final[str] = 'epydemic.opinion.G': Compartment for nodes ignorant of the rumour.

Opinion.SPREADER: Final[str] = 'epydemic.opinion.P': Compartment for nodes spreading the rumour.

Opinion.STIFLER: Final[str] = 'epydemic.opinion.T': Compartment for nodes now stifling the rumour.

Parameters

The process is parameterised by three parameters:

Opinion.P_AFFECTED: Final[float] = 'epydemic.opinion.pAffected': Parameter for probability of initially being affected at start.

Opinion.P_AFFECT: Final[float] = 'epydemic.opinion.pAffect': Parameter for probability of affect on contact.

Opinion.P_STIFLE: Final[float] = 'epydemic.opinion.pStifle': Parameter for probability of becoming stifler on contact.

Loci

Opinion spreading uses two loci:

Between ignorant and spreader nodes (GP edges), where the opinion is spread (the Opinion.GP locus); and
Between spreaders and spreaders or stiflers (PPT edges) where the opinion is quashed (the Opinion.PPT locus).

Opinion.GP: Final[str] = 'epydemic.opinion.GP': Compartment for edges able to transmit the rumour.

Opinion.PPT: Final[str] = 'epydemic.opinion.PPT': Compartment for edges able to stifle the rumour.

Building the model

Opinion.build(params)

Build the opinion model.

Parameters:: params (Dict[str, Any]) – the experimental parameters

Event methods

Opinion.affect(t, e)

Performs affect event. Changes the compartment of the ignorant-end node to SPREADER. This is recorded in the state as occupying the edge over which the opinion passed, as as a “hit” for the hitting time.

Parameters:

t (float) – the simulation time
e (Union[Any, Tuple[Any, Any]]) – the edge transmitting the infection, ignorant -> spreader

Opinion.stifle(t, e)

Performs a stifle event. This changes the compartment of a SPREADER node to STIFLER.

Parameters:

t (float) – the simulation time (unused)
e (Union[Any, Tuple[Any, Any]]) – the edge, spreader -> (spreader or stifler)

Running the model

Opinion.atEquilibrium(t)

The process is at equilibrium if there are no more GP or PPT edges remaining.

Parameters:: t (float) – the simulation time
Return type:: bool
Returns:: True if the process is at equilibrium

Opinion: An opinion dynamics process