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.

__call__(individual: Any) → Optional[Any]

Make this characteristic callable.

This method should be overridden in sub-classes.

Parameters:: individual (object) – Any python object.
Returns:: The individual characteristic.
Return type:: Optional[Any]

Hint

If the returned value is None, the characteristic is undetermined.

__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: bool

Get the cache property.

Returns:: The cache property.
Return type:: bool

clear() → None: Clear the cache.

property components: Sequence[galactic.characteristics.Characteristic]

Get the inner characteristics.

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

property explanation: Optional[str]

Get the explanation.

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

property label: Optional[str]

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: Optional[str]

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: Optional[str]

Get the label.

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

property space: Sequence[galactic.characteristics.Characteristic]

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
>>>

__call__(individual: Any) → Optional[Any]

Make this characteristic callable.

This method should be overridden in sub-classes.

Parameters:: individual (object) – Any python object.
Returns:: The individual characteristic.
Return type:: Optional[Any]

Hint

If the returned value is None, the characteristic is undetermined.

__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: bool

Get the cache property.

Returns:: The cache property.
Return type:: bool

property characteristic: Optional[galactic.characteristics.Characteristic]

Get the inner characteristic.

Returns:: The inner characteristic.
Return type:: Characteristic

clear() → None: Clear the cache.

property components: Sequence[galactic.characteristics.Characteristic]

Get the inner characteristics.

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

property explanation: Optional[str]

Get the explanation.

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

property label: Optional[str]

Get the label.

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

property name: Hashable

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

__call__(individual: Any) → Optional[Any]

Make this characteristic callable.

This method should be overridden in sub-classes.

Parameters:: individual (object) – Any python object.
Returns:: The individual characteristic.
Return type:: Optional[Any]

Hint

If the returned value is None, the characteristic is undetermined.

__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: bool

Get the cache property.

Returns:: The cache property.
Return type:: bool

property characteristic: Optional[galactic.characteristics.Characteristic]

Get the inner characteristic.

Returns:: The inner characteristic.
Return type:: Characteristic

clear() → None: Clear the cache.

property components: Sequence[galactic.characteristics.Characteristic]

Get the inner characteristics.

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

property data: Hashable

Get the value.

Returns:: The value.
Return type:: Hashable

property explanation: Optional[str]

Get the explanation.

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

property label: Optional[str]

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.

__call__(individual: Any) → Optional[Any]

Make this characteristic callable.

This method should be overridden in sub-classes.

Parameters:: individual (object) – Any python object.
Returns:: The individual characteristic.
Return type:: Optional[Any]

Hint

If the returned value is None, the characteristic is undetermined.

__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: bool

Get the cache property.

Returns:: The cache property.
Return type:: bool

clear() → None: Clear the cache.

property components: Sequence[galactic.characteristics.Characteristic]

Get the inner characteristics.

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

property explanation: Optional[str]

Get the explanation.

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

property label: Optional[str]

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.

__call__(individual: Any) → Optional[Any]

Make this characteristic callable.

This method should be overridden in sub-classes.

Parameters:: individual (object) – Any python object.
Returns:: The individual characteristic.
Return type:: Optional[Any]

Hint

If the returned value is None, the characteristic is undetermined.

__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: bool

Get the cache property.

Returns:: The cache property.
Return type:: bool

clear() → None: Clear the cache.

property components: Sequence[galactic.characteristics.Characteristic]

Get the inner characteristics.

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

property explanation: Optional[str]

Get the explanation.

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

property label: Optional[str]

Get the label.

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