from __future__ import annotations
import copy
import glob
import importlib
import inspect
import logging
import os
import yaml
from pathlib import Path
import sys
import traceback
import typing
from typing import (
TYPE_CHECKING,
Any,
Callable,
Dict,
List,
Optional,
Sequence,
Type,
Union,
)
import importlib
from policyengine_core import commons, periods, variables
from policyengine_core.data_structures.reference import Reference
from policyengine_core.entities import Entity
from policyengine_core.errors import (
VariableNameConflictError,
VariableNotFoundError,
)
from policyengine_core.parameters import ParameterNode, ParameterNodeAtInstant
from policyengine_core.parameters.operations.homogenize_parameters import (
homogenize_parameter_structures,
)
from policyengine_core.parameters.operations.interpolate_parameters import (
interpolate_parameters,
)
from policyengine_core.parameters.operations.propagate_parameter_metadata import (
propagate_parameter_metadata,
)
from policyengine_core.parameters.operations.uprate_parameters import (
uprate_parameters,
)
from policyengine_core.periods import Instant, Period
from policyengine_core.populations import GroupPopulation, Population
from policyengine_core.variables import Variable
log = logging.getLogger(__name__)
[docs]class TaxBenefitSystem:
"""
Represents the legislation.
It stores parameters (values defined for everyone) and variables (values defined for some given entity e.g. a person).
Attributes:
parameters: Directory containing the YAML parameter files.
Args:
entities: Entities used by the tax benefit system.
"""
_base_tax_benefit_system: "TaxBenefitSystem" = None
_parameters_at_instant_cache: Optional[Dict[Any, Any]] = None
person_key_plural: str = None
preprocess_parameters: str = None
baseline: "TaxBenefitSystem" = (
None # Baseline tax-benefit system. Used only by reforms. Note: Reforms can be chained.
)
cache_blacklist = None
decomposition_file_path = None
variable_module_metadata: dict = None
# The following properties should be specified by country packages.
entities: List[Entity] = None
"""The entities of the tax and benefit system."""
variables_dir: str = None
"""Directory containing the Python files defining the variables of the tax and benefit system."""
parameters_dir: str = None
"""Directory containing the YAML parameter tree."""
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."""
modelled_policies: str = None
"""A YAML filepath containing metadata describing the modelled policies."""
def __init__(self, entities: Sequence[Entity] = None, reform=None) -> None:
if entities is None:
entities = self.entities
if entities is None:
raise ValueError("TaxBenefitSystems must have entities defined.")
# TODO: Currently: Don't use a weakref, because they are cleared by Paste (at least) at each call.
self.parameters: Optional[ParameterNode] = None
self._parameters_at_instant_cache = {} # weakref.WeakValueDictionary()
self.variables: Dict[Any, Any] = {}
# Tax benefit systems are mutable, so entities (which need to know about our variables) can't be shared among them
if entities is None or len(entities) == 0:
raise Exception(
"A tax and benefit sytem must have at least an entity."
)
self.entities = [copy.copy(entity) for entity in entities]
self.person_entity = [
entity for entity in self.entities if entity.is_person
][0]
self.group_entities = [
entity for entity in self.entities if not entity.is_person
]
self.group_entity_keys = [entity.key for entity in self.group_entities]
for entity in self.entities:
entity.set_tax_benefit_system(self)
self.variable_module_metadata = {}
if self.variables_dir is not None:
self.add_variables_from_directory(self.variables_dir)
if self.parameters_dir is not None:
self.load_parameters(self.parameters_dir)
self.parameters.add_child("baseline", self.parameters.clone())
if reform:
self.apply_reform_set(reform)
self.parameters = homogenize_parameter_structures(
self.parameters, self.variables
)
self.parameters = propagate_parameter_metadata(self.parameters)
self.parameters = interpolate_parameters(self.parameters)
self.parameters = uprate_parameters(self.parameters)
self.parameters = propagate_parameter_metadata(self.parameters)
self.add_abolition_parameters()
self.add_modelled_policy_metadata()
def apply_reform_set(self, reform):
if isinstance(reform, tuple):
for subreform in reform:
self.apply_reform_set(subreform)
else:
reform.apply(self)
def add_abolition_parameters(self):
if self.parameters is None or "gov" not in self.parameters.children:
return
abolition_folder_data = {
"metadata": {
"label": "Abolitions",
}
}
for variable in self.variables.values():
if variable.is_input_variable() or variable.value_type not in (
bool,
float,
int,
):
continue
abolition_folder_data[variable.name] = {
"description": f"Set all values of {variable.label} to zero.",
"values": {
"0000-01-01": False,
},
"metadata": {
"label": f"Abolish {variable.label}",
"unit": "bool",
},
}
if not "abolitions" in self.parameters.gov.children:
self.parameters.gov.add_child(
"abolitions",
ParameterNode(
name="gov.abolitions", data=abolition_folder_data
),
)
@property
def base_tax_benefit_system(self) -> "TaxBenefitSystem":
base_tax_benefit_system = self._base_tax_benefit_system
if base_tax_benefit_system is None:
baseline = self.baseline
if baseline is None:
return self
self._base_tax_benefit_system = base_tax_benefit_system = (
baseline.base_tax_benefit_system
)
return base_tax_benefit_system
def instantiate_entities(self) -> Dict[str, Population]:
person = self.person_entity
members = Population(person)
entities: typing.Dict[Entity.key, Entity] = {person.key: members}
for entity in self.group_entities:
entities[entity.key] = GroupPopulation(entity, members)
return entities
def load_variable(
self, variable_class: Type[Variable], update: bool = False
) -> Variable:
name = variable_class.__name__
# Check if a Variable with the same name is already registered.
baseline_variable = self.get_variable(name)
if baseline_variable and not update:
raise VariableNameConflictError(
f"You've already defined {name} in {baseline_variable.module_name}. You tried to define it again in {variable_class.module_name}."
)
variable = variable_class(baseline_variable=baseline_variable)
self.variables[variable.name] = variable
return variable
[docs] def add_variable(self, variable: Variable) -> Variable:
"""Adds an OpenFisca variable to the tax and benefit system.
Args:
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.
"""
return self.load_variable(variable, update=False)
[docs] def replace_variable(self, variable: str) -> Variable:
"""
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.
:param Variable variable: New variable to add. Must be a subclass of Variable.
"""
name = variable.__name__
if self.variables.get(name) is not None:
del self.variables[name]
self.load_variable(variable, update=False)
[docs] def update_variable(self, variable: str) -> Variable:
"""
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.
:param Variable variable: Variable to add. Must be a subclass of Variable.
"""
return self.load_variable(variable, update=True)
[docs] def add_variables_from_file(self, file_path: str) -> None:
"""
Adds all OpenFisca variables contained in a given file to the tax and benefit system.
"""
try:
file_name = os.path.splitext(os.path.basename(file_path))[0]
path = Path(file_path)
# Get the relative location, e.g. policyengine_uk/variables/gov/child_benefit.py -> gov.child_benefit
try:
relative_file_path = (
str(path.relative_to(self.variables_dir))
.replace("/", ".")
.replace(".py", "")
)
except:
relative_file_path = ""
# As Python remembers loaded modules by name, in order to prevent collisions, we need to make sure that:
# - Files with the same name, but located in different directories, have a different module names. Hence the file path hash in the module name.
# - The same file, loaded by different tax and benefit systems, has distinct module names. Hence the `id(self)` in the module name.
module_name = (
f"{id(self)}_{hash(os.path.abspath(file_path))}_{file_name}"
)
try:
spec = importlib.util.spec_from_file_location(
module_name, file_path
)
module = importlib.util.module_from_spec(spec)
sys.modules[module_name] = module
spec.loader.exec_module(module)
except NameError as e:
logging.error(
str(e)
+ ": if this code used to work, this error might be due to a major change in OpenFisca-Core. Checkout the changelog to learn more: <https://github.com/openfisca/openfisca-core/blob/master/CHANGELOG.md>"
)
raise
potential_variables = [
getattr(module, item)
for item in module.__dict__
if not item.startswith("__")
]
metadata = {}
metadata["label"] = module.__dict__.get(
"label", relative_file_path
)
metadata["description"] = module.__dict__.get("description", None)
metadata["index"] = module.__dict__.get("index", 0)
self.variable_module_metadata[relative_file_path] = metadata
i = 0
for pot_variable in potential_variables:
# We only want to get the module classes defined in this module (not imported)
if (
inspect.isclass(pot_variable)
and issubclass(pot_variable, Variable)
and pot_variable.__module__ == module_name
):
pot_variable.module_name = relative_file_path
pot_variable.index_in_module = i
i += 1
self.add_variable(pot_variable)
except Exception:
log.error(
'Unable to load OpenFisca variables from file "{}"'.format(
file_path
)
)
raise
[docs] def add_variables_from_directory(self, directory: str) -> None:
"""
Recursively explores a directory, and adds all OpenFisca variables found there to the tax and benefit system.
"""
py_files = glob.glob(os.path.join(directory, "*.py"))
# Try to get the __init__.py file. The __init__.py file may contain metadata about the directory.
init_module = os.path.join(directory, "__init__.py")
if init_module in py_files:
# Extract the label and description from the __init__.py file
py_files.remove(init_module)
self.add_variable_metadata_from_folder(init_module)
if "README.md" in os.listdir(directory):
self.add_variable_metadata_from_folder(
os.path.join(directory, "README.md")
)
for py_file in py_files:
self.add_variables_from_file(py_file)
subdirectories = glob.glob(os.path.join(directory, "*/"))
for subdirectory in subdirectories:
self.add_variables_from_directory(subdirectory)
[docs] def add_variables(self, *variables: List[Type[Variable]]):
"""
Adds a list of OpenFisca Variables to the `TaxBenefitSystem`.
See also :any:`add_variable`
"""
for variable in variables:
self.add_variable(variable)
[docs] def load_extension(self, extension: str) -> None:
"""
Loads an extension to the tax and benefit system.
:param str extension: 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 extension from installed pip package
try:
package = importlib.import_module(extension)
extension_directory = package.__path__[0]
except ImportError:
message = os.linesep.join(
[
traceback.format_exc(),
"Error loading extension: `{}` is neither a directory, nor a package.".format(
extension
),
"Are you sure it is installed in your environment? If so, look at the stack trace above to determine the origin of this error.",
"See more at <https://github.com/openfisca/openfisca-extension-template#installing>.",
]
)
raise ValueError(message)
self.add_variables_from_directory(extension_directory)
param_dir = os.path.join(extension_directory, "parameters")
if os.path.isdir(param_dir):
extension_parameters = ParameterNode(directory_path=param_dir)
self.parameters.merge(extension_parameters)
[docs] def get_variable(
self, variable_name: str, check_existence: bool = False
) -> Variable:
"""
Get a variable from the tax and benefit system.
:param variable_name: Name of the requested variable.
:param check_existence: If True, raise an error if the requested variable does not exist.
"""
variables = self.variables
found = variables.get(variable_name)
if not found and check_existence:
raise VariableNotFoundError(variable_name, self)
return found
[docs] def neutralize_variable(self, variable_name: str) -> None:
"""
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.
"""
self.variables[variable_name] = variables.get_neutralized_variable(
self.get_variable(variable_name)
)
def annualize_variable(
self, variable_name: str, period: typing.Optional[Period] = None
):
self.variables[variable_name] = variables.get_annualized_variable(
self.get_variable(variable_name, period)
)
[docs] def load_parameters(
self,
path_to_yaml_dir: str,
) -> None:
"""
Loads the legislation parameter for a directory containing YAML parameters files.
:param path_to_yaml_dir: Absolute path towards the YAML parameter directory.
Example:
>>> self.load_parameters('/path/to/yaml/parameters/dir')
"""
parameters = ParameterNode(
"",
directory_path=path_to_yaml_dir,
)
if self.preprocess_parameters is not None:
parameters = self.preprocess_parameters(parameters)
self.parameters = parameters
def _get_baseline_parameters_at_instant(
self, instant: Instant
) -> ParameterNodeAtInstant:
baseline = self.baseline
if baseline is None:
return self.get_parameters_at_instant(instant)
return baseline._get_baseline_parameters_at_instant(instant)
[docs] def get_parameters_at_instant(
self, instant: Instant
) -> ParameterNodeAtInstant:
"""
Get the parameters of the legislation at a given instant
:param instant: :obj:`str` of the format 'YYYY-MM-DD' or :class:`.Instant` instance.
:returns: The parameters of the legislation at a given instant.
:rtype: :class:`.ParameterNodeAtInstant`
"""
if isinstance(instant, Period):
instant = instant.start
elif isinstance(instant, (str, int)):
instant = periods.instant(instant)
else:
assert isinstance(
instant, Instant
), "Expected an Instant (e.g. Instant((2017, 1, 1)) ). Got: {}.".format(
instant
)
parameters_at_instant = self._parameters_at_instant_cache.get(instant)
if parameters_at_instant is None and self.parameters is not None:
parameters_at_instant = self.parameters.get_at_instant(
str(instant)
)
self._parameters_at_instant_cache[instant] = parameters_at_instant
return parameters_at_instant
[docs] def get_variables(self, entity: Entity = None) -> dict:
"""
Gets all variables contained in a tax and benefit system.
:param Entity entity: If set, returns only the variable defined for the given entity.
:returns: A dictionary, indexed by variable names.
:rtype: dict
"""
if not entity:
return self.variables
else:
return {
variable_name: variable
for variable_name, variable in self.variables.items()
# TODO - because entities are copied (see constructor) they can't be compared
if variable.entity.key == entity.key
}
def clone(self) -> "TaxBenefitSystem":
new = commons.empty_clone(self)
new_dict = new.__dict__
for key, value in self.__dict__.items():
if key not in (
"parameters",
"_parameters_at_instant_cache",
"variables",
):
new_dict[key] = value
new_dict["parameters"] = self.parameters.clone()
new_dict["_parameters_at_instant_cache"] = {}
new_dict["variables"] = {
variable_name: variable.clone()
for variable_name, variable in self.variables.items()
}
for entity in new_dict["entities"]:
entity.set_tax_benefit_system(new)
return new
def entities_plural(self) -> dict:
return {entity.plural for entity in self.entities}
def entities_by_singular(self) -> dict:
return {entity.key: entity for entity in self.entities}
def test(self, paths: str, verbose: bool = False) -> None:
from policyengine_core.tools.test_runner import (
run_tests,
) # Import here to avoid circular dependency.
run_tests(self, paths, options=dict(verbose=verbose))
[docs] def modify_parameters(
self, modifier_function: Callable[[ParameterNode], ParameterNode]
) -> None:
"""Make modifications on the parameters of the legislation.
Call this function in `apply()` if the reform asks for legislation parameter modifications.
Args:
modifier_function: A function that takes a :obj:`.ParameterNode` and should return an object of the same type.
"""
reform_parameters = modifier_function(self.parameters)
if not isinstance(reform_parameters, ParameterNode):
return ValueError(
"modifier_function {} in module {} must return a ParameterNode".format(
modifier_function.__name__,
modifier_function.__module__,
)
)
self.parameters = reform_parameters
self._parameters_at_instant_cache = {}