firecrown.parameters

Classes and functions to support groups of named parameters.

These are used in Firecrown in preference to the Python dictionary in order to provide better type safety.

Classes

ParamsMap	A specialized dict in which all keys are strings and values are floats.
RequiredParameters	Represents a sequence of parameter names.
DerivedParameter	Represents a derived scalar parameter generated by an Updatable object.
DerivedParameterCollection	Represents a list of DerivedParameter objects.
SamplerParameter	Class to represent a sampler defined parameter.
InternalParameter	Class to represent an internally defined parameter.

Functions

parameter_get_full_name(prefix, param)	Form a full parameter name from the given (optional) prefix and name.
register_new_updatable_parameter([value])	Create a new parameter, either a SamplerParameter or an InternalParameter.

Module Contents

firecrown.parameters.parameter_get_full_name(prefix, param)

Form a full parameter name from the given (optional) prefix and name.

Parameter names, as stored in SACC, for example, contain an optional prefix; if a prefix is present, it will be separated from the name by an underscore.

Prefixes and names should avoid containing embedded underscores. This is currently not enforced in the code.

The parameter name can not be empty, even if accompanied by a prefix; this is enforced in the code.

Parameters:

• prefix (None | str) – optional prefix

• param (str) – name

Returns:

full name

Raises:

ValueError – if the parameter name is empty

Return type:

str

class firecrown.parameters.ParamsMap(*args, **kwargs)

Bases: dict[str, float]

A specialized dict in which all keys are strings and values are floats.

The recommended access method is get_from_prefix_param, rather than indexing with square brackets like x[].

lower_case: bool = False

use_lower_case_keys(enable)

Control whether keys will be translated into lower case.

If enable is True, such translation will be done. This can help make sure code works with CosmoSIS, because such translation is done inside CosmoSIS itself.

Parameters:

enable (bool) – whether to enable or disable this option

Return type:

None

get_from_full_name(full_name)

Return the parameter identified by the full name.

Raises a KeyError if the parameter is not found.

Parameters:

full_name (str)

Return type:

float

get_from_prefix_param(prefix, param)

Return the parameter identified by the optional prefix and parameter name.

See parameter_get_full_name for rules on the forming of prefix and name. Raises a KeyError if the parameter is not found.

Parameters:

• prefix (None | str)

• param (str)

Return type:

float

class firecrown.parameters.RequiredParameters(params)

Represents a sequence of parameter names.

This class provides some type safety to distinguish between an arbitrary list of strings, and one intended to be a list of required parameter names.

An instance can be created from a list of strings. Instances can be concatenated using +, and compared for equality using ==.

To iterate through the names (which are strings), use get+params_names, which implements lazy evaluation.

Parameters:

params (Iterable[SamplerParameter])

params_set: set[SamplerParameter]

__len__()

Return the number of parameters contained.

__add__(other)

Return a new RequiredParameters with the concatenated names.

Note that this function returns a new object that does not share state with either argument to the addition operator.

Parameters:

other (RequiredParameters)

Return type:

RequiredParameters

__sub__(other)

Return a new RequiredParameters with the names in self but not in other.

Note that this function returns a new object that does not share state with either argument to the subtraction operator.

Parameters:

other (RequiredParameters)

Return type:

RequiredParameters

__eq__(other)

Compare two RequiredParameters objects for equality.

This implementation raises a NotImplemented exception unless both objects are RequireParameters objects.

Two RequireParameters objects are equal if their contained names are equal (including appearing in the same order).

Parameters:

other (object)

get_params_names()

Implement lazy iteration through the contained parameter names.

Return type:

Iterator[str]

get_default_values()

Return a dictionary with the default values of the parameters.

Return type:

dict[str, float]

class firecrown.parameters.DerivedParameter(section, name, val)

Represents a derived scalar parameter generated by an Updatable object.

This class provide the type that encapsulate a derived scalar quantity (represented

by a float) computed by an Updatable object during a statistical analysis.

Parameters:

• section (str)

• name (str)

• val (float)

section: str

name: str

val: float

get_val()

Return the value of this parameter.

Return type:

float

__eq__(other)

Compare two DerivedParameter objects for equality.

This implementation raises a NotImplemented exception unless both objects are DerivedParameter objects.

Two DerivedParameter objects are equal if they have the same section, name and value.

Parameters:

other (object)

Return type:

bool

get_full_name()

Constructs the full name using section–name.

class firecrown.parameters.DerivedParameterCollection(derived_parameters)

Represents a list of DerivedParameter objects.

Parameters:

derived_parameters (Sequence[DerivedParameter])

derived_parameters: dict[str, DerivedParameter]

__len__()

Return the number of parameters contained.

Return type:

int

__add__(other)

Add two DerivedParameterCollection objects.

Return a new DerivedParameterCollection with the lists of DerivedParameter objects.

If other is none return self. Otherwise, constructs a new object representing the addition.

Note that this function returns a new object that does not share state with either argument to the addition operator.

Parameters:

other (None | DerivedParameterCollection)

__eq__(other)

Compare two DerivedParameterCollection objects for equality.

This implementation raises a NotImplemented exception unless both objects are DerivedParameterCollection objects.

Two DerivedParameterCollection objects are equal if they contain the same DerivedParameter objects.

Parameters:

other (object)

__iter__()

Implementation of lazy iteration through the collection.

Return type:

Iterator[tuple[str, str, float]]

add_required_parameter(derived_parameter)

Adds derived_parameter to the collection.

We raises an ValueError if a required parameter with the same name is already present in the collection.

Parameters:

derived_parameter (DerivedParameter)

get_derived_list()

Implement lazy iteration through the contained parameter names.

Return type:

list[DerivedParameter]

class firecrown.parameters.SamplerParameter(*, default_value, name=None, prefix=None)

Class to represent a sampler defined parameter.

Parameters:

• default_value (float)

• name (None | str)

• prefix (None | str)

default_value

get_default_value()

Get the default value of this parameter.

Return type:

float

set_fullname(prefix, name)

Set the prefix of this parameter.

Parameters:

• prefix (str | None) – new prefix

• name (str)

property prefix: str | None

Get the prefix of this parameter.

Return type:

str | None

property name: str

Get the name of this parameter.

Return type:

str

property fullname: str

Get the full name of this parameter.

Return type:

str

__hash__()

Return the hash of the full name of this parameter.

Return type:

int

__eq__(other)

Return whether this parameter is equal to another.

Two SamplerParameter objects are equal if they have the same full name.

Parameters:

other (object)

Return type:

bool

class firecrown.parameters.InternalParameter(value)

Class to represent an internally defined parameter.

Parameters:

value (float)

value

set_value(value)

Set the value of this parameter.

Parameters:

value (float) – new value

get_value()

Return the current value of this parameter.

Return type:

float

firecrown.parameters.register_new_updatable_parameter(value=None, *, default_value)

Create a new parameter, either a SamplerParameter or an InternalParameter.

If value is None, the result will be a SamplerParameter; Firecrown will expect this value to be supplied by the sampling framework. If value is a float quantity, then Firecrown will expect this parameter to not be supplied by the sampling framework, and instead the provided value will be used for every sample.

Only None or a float value is allowed.

Parameters:

• value (None | float) – the value of the parameter

• default_value (float) – the default value of the parameter to be used if value is None

Returns:

a SamplerParameter if value is None, otherwise an InternalParameter

Raises:

TypeError – if value is not None and not a float