Auto Ownership

The auto ownership model selects a number of autos for each household in the simulation. The primary model components are household demographics, zonal density, and accessibility.

Structure

• Configuration File: auto_ownership.yaml

• Core Table: households

• Result Field: auto_owenership

This model is typically structured as multinomial logit model.

Configuration

settings activitysim.abm.models.auto_ownership.AutoOwnershipSettings

Bases: LogitComponentSettings

Settings for the auto_ownership component.

Fields:

• COEFFICIENTS (pathlib.Path | None)

• CONSTANTS (dict[str, typing.Any])

• LOGIT_TYPE (Literal['MNL', 'NL'])

• NESTS (activitysim.core.configuration.logit.LogitNestSpec | None)

• SPEC (pathlib.Path)

• sharrow_skip (bool)

• source_file_paths (list[pathlib.Path])

Validators:

• nests_are_for_nl » NESTS

field COEFFICIENTS: Path | None = None

Coefficients filename.

This is a CSV file giving named parameters for use in the utility expression. If it is not provided, then it is assumed that all model coefficients are given explicitly in the SPEC as numerical values instead of named parameters. This is perfectly acceptable for use with ActivitySim for typical simulation applications, but may be problematic if used with “estimation mode”.

field CONSTANTS: dict[str, Any] = {}

Named constants usable in the utility expressions.

field LOGIT_TYPE: Literal['MNL', 'NL'] = 'MNL'

Logit model mathematical form.

• “MNL”

  Multinomial logit model.

• “NL”

  Nested multinomial logit model.

field NESTS: LogitNestSpec | None = None

Nesting structure for a nested logit model.

The nesting structure is specified heirarchically from the top, so the value of this field should be the “root” level nest of the nested logit tree, which should contain references to lower level nests and/or the actual alternatives.

For example, this YAML defines a simple nesting structure for four alternatives (DRIVE, WALK, WALK_TO_TRANSIT, DRIVE_TO_TRANSIT) with the two transit alternatives grouped together in a nest:

NESTS:
  name: root
  coefficient: coef_nest_root
  alternatives:
    - DRIVE
    - WALK
    - name: TRANSIT
      coefficient: coef_nest_transit
      alternatives:
      - WALK_TO_TRANSIT
      - DRIVE_TO_TRANSIT

Validated by:

• nests_are_for_nl

field SPEC: Path [Required]

Utility specification filename.

This is sometimes alternatively called the utility expressions calculator (UEC). It is a CSV file giving all the functions for the terms of a linear-in-parameters utility expression.

field sharrow_skip: bool = False

Skip sharrow when evaluating this component.

field source_file_paths: list[Path] = None

A list of source files from which these settings were loaded.

This value should not be set by the user within the YAML settings files, instead it is populated as those files are loaded. It is primarily provided for debugging purposes, and does not actually affect the operation of any model.

validator nests_are_for_nl  »  NESTS

Checks that nests are provided if (and only if) LOGIT_TYPE is NL.

Examples

• Prototype MTC

• Prototype ARC

Implementation

activitysim.abm.models.auto_ownership.auto_ownership_simulate(state: State, households: DataFrame, households_merged: DataFrame, model_settings: Optional[AutoOwnershipSettings] = None, model_settings_file_name: str = 'auto_ownership.yaml', trace_label: str = 'auto_ownership_simulate', trace_hh_id: bool = False) → None

Auto ownership is a standard model which predicts how many cars a household with given characteristics owns