Tax-benefit systems#

The policyengine_core.taxbenefitsystems module contains the definition of TaxBenefitSystem, the class that represents a country’s tax-benefit system: the logic, parameters and entities, not the input data.

TaxBenefitSystem#

class policyengine_core.taxbenefitsystems.tax_benefit_system.TaxBenefitSystem(entities: Optional[Sequence[policyengine_core.entities.entity.Entity]] = None, reform=None)[source]#

Bases: object

Represents the legislation.

It stores parameters (values defined for everyone) and variables (values defined for some given entity e.g. a person).

parameters#

Directory containing the YAML parameter files.

Parameters

entities – Entities used by the tax benefit system.

add_modelled_policy_metadata()[source]#

Adds metadata to variables that are modelled by PolicyEngine.

add_variable(variable: policyengine_core.variables.variable.Variable) policyengine_core.variables.variable.Variable[source]#

Adds an OpenFisca variable to the tax and benefit system.

Parameters

variable – The variable to add. Must be a subclass of Variable.

Raises

policyengine_core.errors.VariableNameConflictError – if a variable with the same name have previously been added to the tax and benefit system.

add_variable_metadata_from_folder(file_path: str) None[source]#

Adds metadata from a given README.md file to the tax and benefit system.

add_variables(*variables: List[Type[policyengine_core.variables.variable.Variable]])[source]#

Adds a list of OpenFisca Variables to the TaxBenefitSystem.

See also add_variable

add_variables_from_directory(directory: str) None[source]#

Recursively explores a directory, and adds all OpenFisca variables found there to the tax and benefit system.

add_variables_from_file(file_path: str) None[source]#

Adds all OpenFisca variables contained in a given file to the tax and benefit system.

apply_reform(reform_path: str) policyengine_core.taxbenefitsystems.tax_benefit_system.TaxBenefitSystem[source]#

Generates a new tax and benefit system applying a reform to the tax and benefit system.

The current tax and benefit system is not mutated.

Parameters

reform_path – The reform to apply. Must respect the format installed_package.sub_module.reform

Returns

A reformed tax and benefit system.

Return type

TaxBenefitSystem

Example

>>> self.apply_reform('openfisca_france.reforms.inversion_revenus')
auto_carry_over_input_variables: bool = False#

Whether to automatically carry over input variables when calculating a variable for a period different from the period of the input variables.

basic_inputs: List[str] = None#

Short list of basic inputs to get medium accuracy.

entities: List[policyengine_core.entities.entity.Entity] = None#

The entities of the tax and benefit system.

get_package_metadata() dict[source]#

Gets metatada relative to the country package the tax and benefit system is built from.

Returns

Country package metadata

Return type

dict

Example:

>>> tax_benefit_system.get_package_metadata()
>>> {
>>>    'location': '/path/to/dir/containing/package',
>>>    'name': 'openfisca-france',
>>>    'repository_url': 'https://github.com/openfisca/openfisca-france',
>>>    'version': '17.2.0'
>>>    }
get_parameters_at_instant(instant: policyengine_core.periods.instant_.Instant) policyengine_core.parameters.parameter_node_at_instant.ParameterNodeAtInstant[source]#

Get the parameters of the legislation at a given instant

Parameters

instantstr of the format ‘YYYY-MM-DD’ or Instant instance.

Returns

The parameters of the legislation at a given instant.

Return type

ParameterNodeAtInstant

get_variable(variable_name: str, check_existence: bool = False) policyengine_core.variables.variable.Variable[source]#

Get a variable from the tax and benefit system.

Parameters
  • variable_name – Name of the requested variable.

  • check_existence – If True, raise an error if the requested variable does not exist.

get_variables(entity: Optional[policyengine_core.entities.entity.Entity] = None) dict[source]#

Gets all variables contained in a tax and benefit system.

Parameters

entity (Entity) – If set, returns only the variable defined for the given entity.

Returns

A dictionary, indexed by variable names.

Return type

dict

load_extension(extension: str) None[source]#

Loads an extension to the tax and benefit system.

Parameters

extension (str) – The extension to load. Can be an absolute path pointing to an extension directory, or the name of an OpenFisca extension installed as a pip package.

load_parameters(path_to_yaml_dir: str) None[source]#

Loads the legislation parameter for a directory containing YAML parameters files.

Parameters

path_to_yaml_dir – Absolute path towards the YAML parameter directory.

Example:

>>> self.load_parameters('/path/to/yaml/parameters/dir')
modelled_policies: str = None#

A YAML filepath containing metadata describing the modelled policies.

modify_parameters(modifier_function: Callable[[policyengine_core.parameters.parameter_node.ParameterNode], policyengine_core.parameters.parameter_node.ParameterNode]) None[source]#

Make modifications on the parameters of the legislation.

Call this function in apply() if the reform asks for legislation parameter modifications.

Parameters

modifier_function – A function that takes a ParameterNode and should return an object of the same type.

neutralize_variable(variable_name: str) None[source]#

Neutralizes an OpenFisca variable existing in the tax and benefit system.

A neutralized variable always returns its default value when computed.

Trying to set inputs for a neutralized variable has no effect except raising a warning.

parameters_dir: str = None#

Directory containing the YAML parameter tree.

replace_variable(variable: str) policyengine_core.variables.variable.Variable[source]#

Replaces an existing OpenFisca variable in the tax and benefit system by a new one.

The new variable must have the same name than the replaced one.

If no variable with the given name exists in the tax and benefit system, no error will be raised and the new variable will be simply added.

Parameters

variable (Variable) – New variable to add. Must be a subclass of Variable.

update_variable(variable: str) policyengine_core.variables.variable.Variable[source]#

Updates an existing OpenFisca variable in the tax and benefit system.

All attributes of the updated variable that are not explicitely overridden by the new variable will stay unchanged.

The new variable must have the same name than the updated one.

If no variable with the given name exists in the tax and benefit system, no error will be raised and the new variable will be simply added.

Parameters

variable (Variable) – Variable to add. Must be a subclass of Variable.

variables_dir: str = None#

Directory containing the Python files defining the variables of the tax and benefit system.