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laser.measles.abm.components.process_importation_pressure

laser.measles.abm.components.process_importation_pressure

laser.measles.abm.components.process_importation_pressure.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), seeding infections into susceptible individuals each tick.

Note

Imported cases are drawn from the total population (binomial(population, rate)), but only susceptible individuals are actually infected. When the number of drawn imports exceeds the available susceptibles in a patch, the excess is discarded. This means the effective importation rate decreases as population immunity increases.

Attributes:

Name Type Description
crude_importation_rate float | list[float] | dict[str, float]

Yearly importation rate per 1,000 total population (not per susceptible). 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). The model converts this to ticks internally, so always supply days regardless of model type. 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::

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params = ImportationPressureParams(crude_importation_rate=0.05)

Disable importation entirely::

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params = ImportationPressureParams(crude_importation_rate=0.0)

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

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# 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::

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# 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)::

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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)::

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

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

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

laser.measles.abm.components.process_importation_pressure.ImportationPressureProcess(model, verbose=False, 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 infected state

Parameters

model : object The simulation model containing nodes, states, and parameters verbose : bool, default=False Whether to print verbose output during simulation params : Optional[ImportationPressureParams], default=None Component-specific parameters. If None, will use default parameters

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