Strategies¶

The galactic.strategies module.

It defines:

the galactic.strategies.Strategy class which is the super-class of all strategies classes;
the galactic.strategies.BasicStrategy class which must be inherited to implement a new strategy;
the galactic.strategies.MetaStrategy class which is the base class for all the meta strategies (strategies that use other strategies);
the galactic.strategies.LimitFilter class which is the a meta strategy which limits the predecessors using a threshold measure;
the galactic.strategies.SelectionFilter class which is the a meta strategy which keeps the predecessors having the best (or the worst) measure;
the galactic.strategies.Measure class which is the base class for all measures. A measure can be called on a set of individuals and must a return a comparable value;
the galactic.strategies.Cardinality which measures the cardinality of a concept;
the galactic.strategies.Support which measures the support of a concept;
the galactic.strategies.Confidence which measures the ratio between the confidence of a concept and its successor;
the galactic.strategies.Explorer class for representing characteristics, descriptions and strategies;

Finally it adds some methods to ConceptLattice:

ConceptLattice.create()
ConceptLattice.apply()

class Measure(label: Optional[str] = None, explanation: Optional[str] = None)¶

The Measure class is an abstract class.

Its subclasses must implement the __call__() method.

abstract __call__(concept: galactic.concepts.Concept, predicate: galactic.descriptions.Predicate) → float ¶

Evaluate the individuals present in the concept whose call to predicate is true.

Parameters

concept (Concept) – The concept for which individuals will be tested.
predicate (Predicate) – The predicate to be tested.

Returns

The computed measure.

Return type

float

__init__(label: Optional[str] = None, explanation: Optional[str] = None)¶

Initialise a Strategy class.

Keyword Arguments

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

property explanation¶

Get the explanation.

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

property label¶

Get the label.

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

class Cardinality(label: Optional[str] = None, explanation: Optional[str] = None)¶

The Cardinality class computes the cardinality of the predecessor.

__call__(concept: galactic.concepts.Concept, predicate: galactic.descriptions.Predicate) → float ¶

Compute the cardinality of the predecessor.

Parameters

concept (Concept) – The concept.
predicate (Predicate) – The predicate.

Returns

The cardinality.

Return type

float

__init__(label: Optional[str] = None, explanation: Optional[str] = None)¶

Initialise a Strategy class.

Keyword Arguments

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

property explanation¶

Get the explanation.

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

property label¶

Get the label.

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

class Confidence(label: Optional[str] = None, explanation: Optional[str] = None)¶

The Confidence class computes the confidence.

It is the cardinality ratio between the predecessor and the successor.

__call__(concept: galactic.concepts.Concept, predicate: galactic.descriptions.Predicate) → float ¶

Compute the confidence of the predecessor.

Parameters

concept (Concept) – The concept.
predicate (Predicate) – The predicate.

Returns

The confidence.

Return type

float

__init__(label: Optional[str] = None, explanation: Optional[str] = None)¶

Initialise a Strategy class.

Keyword Arguments

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

property explanation¶

Get the explanation.

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

property label¶

Get the label.

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

class Support(label: Optional[str] = None, explanation: Optional[str] = None)¶

The Support class computes the support of the predecessor.

__call__(concept: galactic.concepts.Concept, predicate: galactic.descriptions.Predicate) → float ¶

Compute the support of the predecessor.

Parameters

concept (Concept) – The concept.
predicate (Predicate) – The predicate.

Returns

The support.

Return type

float

__init__(label: Optional[str] = None, explanation: Optional[str] = None)¶

Initialise a Strategy class.

Keyword Arguments

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

property explanation¶

Get the explanation.

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

property label¶

Get the label.

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

class Strategy(label: Optional[str] = None, explanation: Optional[str] = None)¶

The Strategy class.

It produces, for a collection of individuals, a collection of candidate predicates.

abstract __call__(concept: galactic.concepts.Concept) → Iterator[galactic.descriptions.Predicate]¶

Produce an iterator of selectors.

Parameters: concept (Concept) – The concept whose selectors are requested.
Returns: An iterator of selectors.
Return type: Iterator[Predicate]

__init__(label: Optional[str] = None, explanation: Optional[str] = None)¶

Initialise a Strategy class.

Keyword Arguments

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

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 BasicStrategy(*characteristics: galactic.characteristics.Characteristic, **kwargs: Any)¶

The BasicStrategy class is used for classical strategies.

abstract __call__(concept: galactic.concepts.Concept) → Iterator[galactic.descriptions.Predicate]¶

Produce an iterator of selectors.

Parameters: concept (Concept) – The concept whose selectors are requested.
Returns: An iterator of selectors.
Return type: Iterator[Predicate]

__init__(*characteristics: galactic.characteristics.Characteristic, **kwargs: Any)¶

Initialise a BasicStrategy instance.

Parameters: *characteristics (Characteristic[Any]) – The underlying characteristics.
Keyword Arguments: **kwargs (Any) – Additional keyword parameters.
Raises: TypeError – If an argument is not an instance of Characteristic[Any].

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 space¶

Get the characteristics.

Returns: An sequence of characteristics.
Return type: Sequence[Characteristic[Any]]

class MetaStrategy(*strategies: galactic.strategies.Strategy, **kwargs: Any)¶

The MetaStrategy class.

It is used for strategy that own their proper inner strategies.

__call__(concept: galactic.concepts.Concept) → Iterator[galactic.descriptions.Predicate]¶

Compute an iterator of selectors.

Parameters: concept (Concept) – The concept whose selectors are requested.
Returns: An iterator of selectors.
Return type: Iterator[Predicate]

__init__(*strategies: galactic.strategies.Strategy, **kwargs: Any) → None ¶

Initialise a MetaStrategy instance.

Parameters: *strategies (Strategy) – A tuple of strategies.
Keyword Arguments: **kwargs (Any) – Additional keyword parameters.
Raises: TypeError – If an argument is not an instance of Strategy

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 strategies¶

Get the strategies.

Returns: The sequence of strategies.
Return type: Sequence[Strategy]

class LimitFilter(*strategies: galactic.strategies.Strategy, limit: SupportsFloat = 0.0, strict: bool = False, lower: bool = True, **kwargs: Any)¶

The LimitFilter class limits the possible predecessors.

It chooses the predecessors whose measure is greater (or less than a threshold).

__call__(concept: galactic.concepts.Concept) → Iterator[galactic.descriptions.Predicate]¶

Produce an iterator or selectors.

Parameters: concept (Concept) – The concept whose selectors are requested.
Returns: The selectors.
Return type: Iterator[Predicate]

__init__(*strategies: galactic.strategies.Strategy, limit: SupportsFloat = 0.0, strict: bool = False, lower: bool = True, **kwargs: Any) → None ¶

Initialise a LimitFilter instance.

Parameters

*strategies (Strategy) – A collection of strategies.

Keyword Arguments

limit (SupportsFloat) – The limit value
strict (bool) – Is the limit strict?
lower (bool) – Is it a lower limit?
**kwargs (Any) – Additional keyword parameters.

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 limit¶

Get the limit.

Returns: The limit.
Return type: float

property lower¶

Get the lower flag.

Returns: The lower flag.
Return type: bool

property measure¶

Get the measure.

Returns: The measure.
Return type: Measure

property strategies¶

Get the strategies.

Returns: The sequence of strategies.
Return type: Sequence[Strategy]

property strict¶

Get the strict flag.

Returns: The strict flag.
Return type: bool

class SelectionFilter(*strategies: galactic.strategies.Strategy, keep: SupportsInt = 1, maximize: bool = True, decrease: bool = True, strict: bool = False, rate: SupportsFloat = 1.0, **kwargs: Any)¶

The SelectionFilter class limits the possible predecessors.

It chooses the predecessors whose measure is among the greatest (or smallest).

__call__(concept: galactic.concepts.Concept) → Iterator[galactic.descriptions.Predicate]¶

Produce an iterator or selectors.

Parameters: concept (Concept) – The concept whose selectors are requested.
Returns: The selectors.
Return type: Iterator[Predicate]

__init__(*strategies: galactic.strategies.Strategy, keep: SupportsInt = 1, maximize: bool = True, decrease: bool = True, strict: bool = False, rate: SupportsFloat = 1.0, **kwargs: Any) → None ¶

Initialise a SelectionFilter instance.

Parameters

*strategies (Strategy) – A tuple of strategies.

Keyword Arguments

keep (SupportsInt) – The number of group having the same value kept by this strategy
maximize (bool) – Does this measure keep the maximum or the minimum predecessors?
decrease (bool) – Does this strategy have to decrease the measure value between a concept and its predecessors.
strict (bool) – Is the comparison strict between the concept and its predecessors.
rate (SupportsFloat) – The rate applied to the concept measure that the predecessors have to be lesser or greater than.
**kwargs (Any) – Additional keyword parameters.

property decrease¶

Get the decrease flag.

Returns: The decrease flag.
Return type: bool

property explanation¶

Get the explanation.

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

property keep¶

Get the keep value.

Returns: The keep value.
Return type: int

property label¶

Get the label.

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

property maximize¶

Get the maximize flag.

Returns: The maximize flag.
Return type: bool

property measure¶

Get the measure.

Returns: The measure.
Return type: Measure

property rate¶

Get the rate value.

Returns: The rate value.
Return type: float

property strategies¶

Get the strategies.

Returns: The sequence of strategies.
Return type: Sequence[Strategy]

property strict¶

Get the strict flag.

Returns: The strict flag.
Return type: int

class ConditionedStrategy(*strategies: galactic.strategies.Strategy, conditions: Iterable[galactic.descriptions.Predicate], **kwargs: Any)¶

The ConditionedStrategy class is conditioned by predicates.

__call__(concept: galactic.concepts.Concept) → Iterator[galactic.descriptions.Predicate]¶

Compute an iterator of selectors.

Parameters: concept (Concept) – The concept whose selectors are requested.
Returns: An iterator of selectors produced by the inner strategies if all conditions are met.
Return type: Iterator[Predicate]

__init__(*strategies: galactic.strategies.Strategy, conditions: Iterable[galactic.descriptions.Predicate], **kwargs: Any) → None ¶

Initialise a ConditionedStrategy instance.

Parameters

*strategies (Strategy) – A sequence of strategies.

Keyword Arguments

conditions (Iterable[Predicate]) – An iterable of predicates
**kwargs (Any) – Additional keyword parameters.

property conditions¶

Get the conditions.

Returns: The conditions.
Return type: Sequence[Predicate]

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 strategies¶

Get the strategies.

Returns: The sequence of strategies.
Return type: Sequence[Strategy]

class Explorer(descriptions: Iterable[galactic.descriptions.Description], strategies: Iterable[galactic.strategies.Strategy], characteristics: Optional[Iterable[galactic.characteristics.Characteristic]] = None, predicates: Optional[Iterable[galactic.descriptions.Predicate]] = None, measures: Optional[Iterable[galactic.strategies.Measure]] = None)¶

The Explorer class holds descriptions and strategies.

__init__(descriptions: Iterable[galactic.descriptions.Description], strategies: Iterable[galactic.strategies.Strategy], characteristics: Optional[Iterable[galactic.characteristics.Characteristic]] = None, predicates: Optional[Iterable[galactic.descriptions.Predicate]] = None, measures: Optional[Iterable[galactic.strategies.Measure]] = None)¶

Initialise an Explorer instance.

Parameters

descriptions (Iterable[Description]) – An iterable of descriptions.
strategies (Iterable[Strategy]) – An iterable of strategies.
characteristics (Optional[Iterable[Characteristics]]) – An iterable of characteristics.
predicates (Optional[Iterable[Predicate]]) – An iterable of predicates.
measures (Optional[Iterable[Measure]]) – An iterable of measures.

property characteristics¶

Get the characteristics of this explorer.

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

property descriptions¶

Get the descriptions of this explorer.

Returns: The descriptions.
Return type: Sequence[Description]

classmethod from_file(stream: TextIO) → galactic.strategies.Explorer ¶

Create an explorer from a readable opened file.

Parameters: stream (TextIO) – File to read
Returns: A new explorer.
Return type: Explorer

property measures¶

Get the measures of this explorer.

Returns: The measures.
Return type: Sequence[Measure]

property predicates¶

Get the predicates of this explorer.

Returns: The characteristics.
Return type: Sequence[Predicate]

property strategies¶

Get the strategies of this explorer.

Returns: The strategies.
Return type: Sequence[Strategy]

write(stream: TextIO) → None ¶

Write an explorer to a file in yaml format.

Parameters: stream (TextIO) – A file to be written

next_priority_concept(closure: galactic.concepts.ConceptClosure, strategies: Sequence[galactic.strategies.Strategy]) → Iterator[Tuple[galactic.concepts.Concept, AbstractSet[galactic.concepts.Concept], AbstractSet[galactic.concepts.Concept]]]¶

Produce a collection of triples (concept, successors, predecessors).

Parameters

closure (ConceptClosure) – The concept closure operator.
strategies (Sequence[Strategy]) – A sequence of descriptions.

Returns

An iterator of all concepts and their successors, predecessors.

Return type

Iterator[Tuple[Concept, AbstractSet[Concept], AbstractSet[Concept]]]

register_classes() → None ¶: Register all classes defined in this module.