Profile Threshold¶
The Profile-Threshold model was introduced in 2017 by Milli et al. [1].
The Profile-Threshold model assumes the existence of node profiles that act as preferential schemas for individual tastes but relax the constraints imposed by the Profile model by letting nodes influenceable via peer pressure mechanisms.
The peer pressure is modeled with a threshold.
The diffusion process starts from a set of nodes that have already adopted a given behaviour S:
- for each of the susceptible node an unbalanced coin is flipped if the percentage of its neighbors that are already infected excedes its threhosld. As in the Profile Model the coin unbalance is given by the personal profile of the susceptible node;
- if a positive result is obtained the susceptible node will adopt the behaviour, thus becoming infected.
- if the blocked status is enabled, after having rejected the adoption with probability
blocked
a node becomes immune to the infection. - every iteration
adopter_rate
percentage of nodes spontaneous became infected to endogenous effects.
Statuses¶
During the simulation a node can experience the following statuses:
Name | Code |
---|---|
Susceptible | 0 |
Infected | 1 |
Blocked | -1 |
Parameters¶
Name | Type | Value Type | Default | Mandatory | Description |
---|---|---|---|---|---|
threshold | Node | float in [0, 1] | 0.1 | False | Individual threshold |
profile | Node | float in [0, 1] | 0.1 | False | Node profile |
blocked | Model | float in [0, 1] | 0 | False | Blocked nodes |
adopter_rate | Model | float in [0, 1] | 0 | False | Autonomous adoption |
The initial infection status can be defined via:
- fraction_infected: Model Parameter, float in [0, 1]
- Infected: Status Parameter, set of nodes
The two options are mutually exclusive and the latter takes precedence over the former.
Methods¶
The following class methods are made available to configure, describe and execute the simulation:
Configure¶
-
class
ndlib.models.epidemics.ProfileThresholdModel.
ProfileThresholdModel
(graph, seed=None)¶ Node Parameters to be specified via ModelConfig
Parameters: - profile – The node profile. As default a value of 0.1 is assumed for all nodes.
- threshold – The node threshold. As default a value of 0.1 is assumed for all nodes.
-
ProfileThresholdModel.
__init__
(graph)¶ Model Constructor
Parameters: graph – A networkx graph object
-
ProfileThresholdModel.
set_initial_status
(self, configuration)¶ Set the initial model configuration
Parameters: configuration – a `ndlib.models.ModelConfig.Configuration`
object
-
ProfileThresholdModel.
reset
(self)¶ Reset the simulation setting the actual status to the initial configuration.
Describe¶
-
ProfileThresholdModel.
get_info
(self)¶ Describes the current model parameters (nodes, edges, status)
Returns: a dictionary containing for each parameter class the values specified during model configuration
-
ProfileThresholdModel.
get_status_map
(self)¶ Specify the statuses allowed by the model and their numeric code
Returns: a dictionary (status->code)
Execute Simulation¶
-
ProfileThresholdModel.
iteration
(self)¶ Execute a single model iteration
Returns: Iteration_id, Incremental node status (dictionary node->status)
-
ProfileThresholdModel.
iteration_bunch
(self, bunch_size)¶ Execute a bunch of model iterations
Parameters: - bunch_size – the number of iterations to execute
- node_status – if the incremental node status has to be returned.
- progress_bar – whether to display a progress bar, default False
Returns: a list containing for each iteration a dictionary {“iteration”: iteration_id, “status”: dictionary_node_to_status}
Example¶
In the code below is shown an example of instantiation and execution of a Profile Threshold model simulation on a random graph: we set the initial infected node set to the 10% of the overall population, assign a profile of 0.25 and a threshold of 0.15 to all the nodes.
import networkx as nx
import ndlib.models.ModelConfig as mc
import ndlib.models.epidemics as ep
# Network topology
g = nx.erdos_renyi_graph(1000, 0.1)
# Model selection
model = ep.ProfileThresholdModel(g)
config = mc.Configuration()
config.add_model_parameter('blocked', 0)
config.add_model_parameter('adopter_rate', 0)
config.add_model_parameter('fraction_infected', 0.1)
# Setting nodes parameters
threshold = 0.15
profile = 0.25
for i in g.nodes():
config.add_node_configuration("threshold", i, threshold)
config.add_node_configuration("profile", i, profile)
model.set_initial_status(config)
# Simulation execution
iterations = model.iteration_bunch(200)
[1] | Letizia Milli, Giulio Rossetti, Dino Pedreschi, Fosca Giannotti, “Information Diffusion in Complex Networks: The Active/Passive Conundrum,” Proceedings of International Conference on Complex Networks and their Applications, (pp. 305-313). Springer, Cham. 2017 |