Descriptions¶

The galactic.descriptions module.

It defines essential classes for representing descriptions:

Description for representing descriptions

And classes for representing predicates:

Predicate for representing predicates
Equal for predicates whose calls to an individual will be retrieved by a equality with a value
Member for predicates whose calls to an individual will be retrieved by a membership test access
Absurd for predicates whose calls to an individual will be always false
Tautology for predicates whose calls to an individual will be always true

class Predicate(*components: galactic.characteristics.Characteristic, cache: bool = True, label: Optional[str] = None, explanation: Optional[str] = None)¶

The Predicate class represents predicate characteristics.

__init__(*components: galactic.characteristics.Characteristic, cache: bool = True, label: Optional[str] = None, explanation: Optional[str] = None) → None ¶

Initialise a Characteristic instance.

Parameters

*components – Inner characteristics (if any).

Keyword Arguments

cache (bool) – Is this characteristic is cached?
label (Optional[str]) – An optional label.
explanation (Optional[str]) – An optional explanation in markdown text.

property cache¶

Get the cache property.

Returns: The cache property.
Return type: bool

clear() → None ¶: Clear the cache.

property components¶

Get the inner characteristics.

Returns: The inner characteristics.
Return type: Sequence[Characteristic]

property explanation¶

Get the explanation.

Returns: The strategy explanation.
Return type: Optional[str]

property label¶

Get the label.

Returns: The strategy label.
Return type: Optional[str]

class Description(*characteristics: galactic.characteristics.Characteristic, label: Optional[str] = None, explanation: Optional[str] = None)¶

The Description class is used to represent description spaces.

A description space must have a __call__() method able to compute the minimal descriptors for a collection of individuals.

abstract __call__(individuals: Iterable[Any]) → Iterator[galactic.descriptions.Predicate]¶

Compute the description of the individuals.

Parameters: individuals (Iterable[Any]) – A collection of individuals
Returns: An iterator over a set of descriptors.
Return type: Iterator[Predicate]
Raises: TypeError – If the argument is not an instance of Iterable[Any]

__init__(*characteristics: galactic.characteristics.Characteristic, label: Optional[str] = None, explanation: Optional[str] = None) → None ¶

Initialise a Description class.

Parameters

*characteristics (Characteristic) – A collection of Characteristic.

Keyword Arguments

label (Optional[str]) – An optional label.
explanation (Optional[str]) – An optional explanation in markdown text.

Raises

RuntimeError – If the number or arguments is not between the minimum and the maximum allowed.
TypeError – If an argument is not an instance of Characteristic

property explanation¶

Get the explanation.

Returns: The strategy explanation.
Return type: Optional[str]

intersection(*predicates: galactic.descriptions.Predicate) → Iterator[galactic.descriptions.Predicate]¶

Compute the intersection of a collection of predicates.

Parameters: *predicates (Predicate) – A collection of predicate
Returns: An iterator of predicates
Return type: Iterator[Predicate]

property label¶

Get the label.

Returns: The strategy label.
Return type: Optional[str]

property space¶

Get the space property.

Returns: The space property
Return type: Sequence[Characteristic[Any]]

class Member(name: Hashable, characteristic: Optional[galactic.characteristics.Characteristic] = None, **kwargs: Any)¶

The Member class is used to represent member predicates.

Example

>>> from galactic.descriptions import Member
>>> a = Member(name="x")
>>> print(a)
x in ~
>>> a({"x"})
True
>>> a({})
False
>>>

__init__(name: Hashable, characteristic: Optional[galactic.characteristics.Characteristic] = None, **kwargs: Any)¶

Initialise a Member instance.

Parameters

name (:class:Hashable <python:typing.Hashable>`) – Any hashable value.
characteristic (Characteristic) – The inner characteristic (if any).
**kwargs – Used for multi-inheritance

property cache¶

Get the cache property.

Returns: The cache property.
Return type: bool

property characteristic¶

Get the inner characteristic.

Returns: The inner characteristic.
Return type: Characteristic

clear() → None ¶: Clear the cache.

property components¶

Get the inner characteristics.

Returns: The inner characteristics.
Return type: Sequence[Characteristic]

property explanation¶

Get the explanation.

Returns: The strategy explanation.
Return type: Optional[str]

property label¶

Get the label.

Returns: The strategy label.
Return type: Optional[str]

property name¶

Get the value.

Returns: The value.
Return type: Hashable

class Equal(data: Hashable, characteristic: Optional[galactic.characteristics.Characteristic] = None, **kwargs: Any)¶

The Equal class represents equality between a characteristic and a value.

Example

>>> from galactic.characteristics import Key
>>> from galactic.descriptions import Equal
>>> a = Equal(data="hello", characteristic=Key(name="x"))
>>> print(a)
x == hello
>>> a(1)
>>> a({})
>>> a({"x": "hello"})
True
>>> a({"x": "good bye"})
False

__init__(data: Hashable, characteristic: Optional[galactic.characteristics.Characteristic] = None, **kwargs: Any)¶

Initialise a Equal instance.

Parameters

data (:class:Hashable <python:typing.Hashable>`) – Any hashable value.
characteristic (Characteristic) – The inner characteristic
**kwargs – Used for multi-inheritance

property cache¶

Get the cache property.

Returns: The cache property.
Return type: bool

property characteristic¶

Get the inner characteristic.

Returns: The inner characteristic.
Return type: Characteristic

clear() → None ¶: Clear the cache.

property components¶

Get the inner characteristics.

Returns: The inner characteristics.
Return type: Sequence[Characteristic]

property data¶

Get the value.

Returns: The value.
Return type: Hashable

property explanation¶

Get the explanation.

Returns: The strategy explanation.
Return type: Optional[str]

property label¶

Get the label.

Returns: The strategy label.
Return type: Optional[str]

class Absurd(*components: galactic.characteristics.Characteristic, cache: bool = True, label: Optional[str] = None, explanation: Optional[str] = None)¶

The Absurd class represent the absurd class. It is always false.

__init__(*components: galactic.characteristics.Characteristic, cache: bool = True, label: Optional[str] = None, explanation: Optional[str] = None) → None ¶

Initialise a Characteristic instance.

Parameters

*components – Inner characteristics (if any).

Keyword Arguments

cache (bool) – Is this characteristic is cached?
label (Optional[str]) – An optional label.
explanation (Optional[str]) – An optional explanation in markdown text.

property cache¶

Get the cache property.

Returns: The cache property.
Return type: bool

clear() → None ¶: Clear the cache.

property components¶

Get the inner characteristics.

Returns: The inner characteristics.
Return type: Sequence[Characteristic]

property explanation¶

Get the explanation.

Returns: The strategy explanation.
Return type: Optional[str]

property label¶

Get the label.

Returns: The strategy label.
Return type: Optional[str]

class Tautology(*components: galactic.characteristics.Characteristic, cache: bool = True, label: Optional[str] = None, explanation: Optional[str] = None)¶

The Tautology class represent the tautology class. It is always true.

__init__(*components: galactic.characteristics.Characteristic, cache: bool = True, label: Optional[str] = None, explanation: Optional[str] = None) → None ¶

Initialise a Characteristic instance.

Parameters

*components – Inner characteristics (if any).

Keyword Arguments

cache (bool) – Is this characteristic is cached?
label (Optional[str]) – An optional label.
explanation (Optional[str]) – An optional explanation in markdown text.

property cache¶

Get the cache property.

Returns: The cache property.
Return type: bool

clear() → None ¶: Clear the cache.

property components¶

Get the inner characteristics.

Returns: The inner characteristics.
Return type: Sequence[Characteristic]

property explanation¶

Get the explanation.

Returns: The strategy explanation.
Return type: Optional[str]

property label¶

Get the label.

Returns: The strategy label.
Return type: Optional[str]