Parameters

The policyengine_core.parameters module contains the classes that define how parameters function. This mainly revolves around the ‘at-instant’ pattern: parameters are defined as a function of time, and are evaluated at a given instant.

Parameter

class policyengine_core.parameters.parameter.Parameter(name: str, data: dict, file_path: Optional[str] = None)

Bases: AtInstantLike

A parameter of the legislation.

Parameters can change over time.

values_list

List of the values, in reverse chronological order.

Parameters:

• name – Name of the parameter, e.g. “taxes.some_tax.some_param”.

• data – Data loaded from a YAML file.

• file_path – File the parameter was loaded from.

Instantiate a parameter without metadata:

>>>  Parameter('rate', data = {
        "2015-01-01": 550,
        "2016-01-01": 600
        })

Instantiate a parameter with metadata:

>>>  Parameter('rate', data = {
        'description': 'Income tax rate applied on salaries',
        'values': {
            "2015-01-01": {'value': 550, 'metadata': {'reference': 'http://taxes.gov/income_tax/2015'}},
            "2016-01-01": {'value': 600, 'metadata': {'reference': 'http://taxes.gov/income_tax/2016'}}
            }
        })

clone()

get_descendants()

update(period=None, start=None, stop=None, value=None)

Change the value for a given period.

Parameters:

• period – Period where the value is modified. If set, start and stop should be None.

• start – Start of the period. Instance of policyengine_core.Instant. If set, period should be None.

• stop – Stop of the period. Instance of policyengine_core.Instant. If set, period should be None.

• value – New value. If None, the parameter is removed from the legislation parameters for the given period.

ParameterNode

class policyengine_core.parameters.parameter_node.ParameterNode(name: str = '', directory_path: Optional[str] = None, data: Optional[dict] = None, file_path: Optional[str] = None)

Bases: AtInstantLike

A node in the legislation parameter tree.

add_child(name: str, child: Union[ParameterNode, Parameter])

Add a new child to the node.

Parameters:

• name – Name of the child that must be used to access that child. Should not contain anything that could interfere with the operator . (dot).

• child – The new child, an instance of ParameterScale or Parameter or ParameterNode.

attach_to_parent(parent: ParameterNode)

clear_parent_cache()

clone() → ParameterNode

get_descendants() → Iterable[Union[ParameterNode, Parameter]]

Return a generator containing all the parameters and nodes recursively contained in this ParameterNode

merge(other: ParameterNode) → None

Merges another ParameterNode into the current node.

In case of child name conflict, the other node child will replace the current node child.

parent: ParameterNode = None

The parent of the node, or None if the node is the root of the tree.

ParameterAtInstant

class policyengine_core.parameters.parameter_at_instant.ParameterAtInstant(name: str, instant_str: str, data: Optional[dict] = None, file_path: Optional[str] = None, metadata: Optional[dict] = None)

Bases: object

A value of a parameter at a given instant.

clone() → ParameterAtInstant

validate(data: dict) → None

ParameterNodeAtInstant

class policyengine_core.parameters.parameter_node_at_instant.ParameterNodeAtInstant(name: str, node: ParameterNode, instant_str: str)

Bases: object

Parameter node of the legislation, at a given instant.

add_child(child_name: str, child_at_instant: ParameterNodeAtInstant)

ParameterScale

class policyengine_core.parameters.parameter_scale.ParameterScale(name: str, data: dict, file_path: str)

Bases: AtInstantLike

A parameter scale (for instance a marginal scale).

clone() → ParameterScale

get_descendants() → Iterable

propagate_units() → None

propagate_uprating() → None

ParameterScaleBracket

class policyengine_core.parameters.parameter_scale_bracket.ParameterScaleBracket(name: str = '', directory_path: Optional[str] = None, data: Optional[dict] = None, file_path: Optional[str] = None)

Bases: ParameterNode

A parameter scale bracket.

static allowed_unit_keys()

get_descendants() → Iterable[Parameter]

Return a generator containing all the parameters and nodes recursively contained in this ParameterNode

propagate_uprating(uprating: str, threshold: bool = False) → None

AtInstantLike

class policyengine_core.parameters.at_instant_like.AtInstantLike

Bases: ABC

Base class for various types of parameters implementing the at instant protocol.

get_at_instant(instant: Instant) → Any

VectorialParameterNodeAtInstant

class policyengine_core.parameters.vectorial_parameter_node_at_instant.VectorialParameterNodeAtInstant(name: str, vector: Union[_SupportsArray[dtype[Any]], _NestedSequence[_SupportsArray[dtype[Any]]], bool, int, float, complex, str, bytes, _NestedSequence[Union[bool, int, float, complex, str, bytes]]], instant_str: str)

Bases: object

Parameter node of the legislation at a given instant which has been vectorized. Vectorized parameters allow requests such as parameters.housing_benefit[zipcode], where zipcode is a vector

static build_from_node(node: ParameterNode) → VectorialParameterNodeAtInstant

static check_node_vectorisable(node: ParameterNode) → None

Check that a node can be casted to a vectorial node, in order to be able to use fancy indexing.

contains_nan

policyengine_core.parameters.helpers.contains_nan(vector)

load_parameter_file

policyengine_core.parameters.helpers.load_parameter_file(file_path, name='')

Load parameters from a YAML file (or a directory containing YAML files).

Returns:

An instance of ParameterNode or ParameterScale or Parameter.