laser.measles.compartmental.components.process_importation_pressure

process_importation_pressure

Component for simulating the importation pressure in the compartmental model.

ImportationPressureParams

Bases: BaseModel

Parameters for the importation pressure component.

Importation pressure simulates external case introductions from outside the modeled population (e.g., international travel, cross-border movement), moving susceptible individuals into the exposed (E) compartment each daily tick.

Note

Unlike the ABM and biweekly models which move S→I, the compartmental model moves imported cases S→E, letting them progress through the latent period.

Attributes:

Name	Type	Description
crude_importation_rate	float | list[float] | dict[str, float]	Yearly importation rate per 1,000 population. Three forms are accepted: float (scalar): uniform rate applied to every patch. 0.0 disables importation entirely. list / tuple / numpy array (sequence): per-patch rates in the same order as model.scenario rows. Length must equal the number of patches. dict[str, float] (sparse patch override): maps patch string ids (values from model.scenario["id"], e.g. "n_0_0", "n_2_2") to rates. Patches absent from the dict receive a rate of 0.0 — they do not inherit the scalar default of 1.0.
importation_start	int	Day on which importation begins (inclusive). Default 0 starts importation at the first tick.
importation_end	int	Day on which importation ends (inclusive). Use -1 (default) to keep importation active for the full simulation. Must be greater than importation_start when not -1.

Examples:

Uniform low background pressure across all patches:

params = ImportationPressureParams(crude_importation_rate=0.05)

Disable importation entirely:

params = ImportationPressureParams(crude_importation_rate=0.0)

Per-patch sequence (one entry per patch, aligned to scenario row order):

# 25-patch model; patch at row index 12 is the metro hub
rates = [0.02] * 25
rates[12] = 0.5
params = ImportationPressureParams(crude_importation_rate=rates)

Sparse dict — only named patches receive importation; all others get 0.0:

# Use string ids from model.scenario["id"], e.g. "n_0_0", "n_2_2"
params = ImportationPressureParams(
    crude_importation_rate={"n_2_2": 0.5, "n_0_0": 0.1},
)

Numpy array input (accepted and converted to list internally):

import numpy as np
params = ImportationPressureParams(
    crude_importation_rate=np.array([0.01, 0.05, 0.01, 0.01, 0.01])
)

Time-windowed importation active only during the first year (days 0-364):

params = ImportationPressureParams(
    crude_importation_rate=0.1,
    importation_start=0,
    importation_end=364,
)

Metro-only importation for the first year, then stop:

params = ImportationPressureParams(
    crude_importation_rate={"n_2_2": 2.0},
    importation_start=0,
    importation_end=364,
)

validate_importation_end(v, info) classmethod

Validate that importation_end is greater than importation_start when not -1.

validate_importation_rate(v) classmethod

Validate that all crude_importation_rate values are non-negative.

ImportationPressureProcess(model, params=None)

Bases: BasePhase

Component for simulating the importation pressure in the model.

This component handles the simulation of disease importation into the population. It processes: - Importation of cases based on crude importation rate - Time-windowed importation (start/end times) - Population updates: Moves individuals from susceptible to exposed state

Parameters:

Name	Type	Description	Default
model	object	The simulation model containing nodes, states, and parameters	required
params	Optional[ImportationPressureParams], default=None	Component-specific parameters. If None, will use default parameters	None

Notes

• Importation rates are calculated per year
• Importation is limited to the susceptible population
• All state counts are ensured to be non-negative

Examples:

from laser.measles.scenarios.synthetic import single_patch_scenario
from laser.measles.compartmental import CompartmentalModel, CompartmentalParams
from laser.measles.compartmental import components
from laser.measles import create_component

scenario = single_patch_scenario(population=100_000, mcv1_coverage=0.85)
params = CompartmentalParams(num_ticks=365, seed=42, start_time="2000-01")
model = CompartmentalModel(scenario, params)
model.add_component(create_component(components.ImportationPressureProcess, components.ImportationPressureParams()))