Strategies¶

The galactic.strategies module defines

the galactic.strategies.Strategy class which is the super-class of all strategies classes;
the galactic.strategies.Strategies class for representing list of strategies;
the galactic.strategies.BasicStrategy class which must be inherited to implement a new strategy;
the galactic.strategies.AbsurdStrategy class which generates no predecessors;
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.PredecessorCardinality which measures the cardinality of the predecessor;
the galactic.strategies.Support which measures the support of an concept;
the galactic.strategies.PredecessorSupport which measures the support of the predecessor;
the galactic.strategies.Confidence which measures the ratio between the confidence of a concept.

class galactic.strategies.Strategy¶

Bases: collections.abc.Hashable

The Strategy class produces, for a collection of individuals, a collection of candidate predicates.

descriptions¶

An iterator over the description spaces linked to this strategy.

Type: Iterator[Description]

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

Compute an iterator over the selectors of a collection of individuals.

Parameters: individuals (Collection) – A collection of individuals.
Returns: An iterator over a collection of selectors.
Return type: Iterator[Predicate]

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

The selectors() method must return an iterator or selectors.

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

abstract descriptions() → Iterator[galactic.descriptions.Description]

Get an iterator over the descriptions.

Returns
Return type: Iterator[Description]

class galactic.strategies.Strategies¶

Bases: typing.List

pass

classmethod from_file(file: io.TextIOBase) → galactic.strategies.Strategies¶

Create a list of strategies from a readable opened file.

Keyword Arguments: file (TextIOBase) – File to read
Returns: A new list of strategies
Return type: Strategies

class galactic.strategies.BasicStrategy¶

Bases: galactic.strategies.Strategy

The BasicStrategy class is used for classical strategies. This class is designed for sub-classing. Sub-classes must set the _description slot in their constructor.

descriptions¶

An iterator over the description spaces linked to this strategy. This iterator iterate over one value.

Type: Iterator[Description]

description¶

The description owned by this strategy.

Type: Description

space¶

The description space of this strategy. This is a proxy to self.description.space.

Type: Tuple[Characteristic]

descriptions() → Iterator[galactic.descriptions.Description]

Get an iterator over the descriptions.

Returns
Return type: Iterator[Description]

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

The selectors() method must return an iterator or selectors.

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

class galactic.strategies.AbsurdStrategy(*args)¶

Bases: galactic.strategies.Strategy

The AbsurdStrategy has been designed to describe individuals using predicates that must not be used for producing concepts.

__init__(*args)¶

Initialize an AbsurdStrategy instance.

Keyword Arguments: *args (Collection[Description]) – A collection of description spaces

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

The selectors() method must return an iterator or selectors.

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

descriptions() → Iterator[galactic.descriptions.Description]¶

Get an iterator over the descriptions.

Returns
Return type: Iterator[Description]

class galactic.strategies.MetaStrategy(*args)¶

Bases: galactic.strategies.Strategy

The MetaStrategy class is used for strategy that own their proper inner strategies.

descriptions¶

An iterator over the description spaces linked to this strategy.

Type: Iterator[Description]

strategies¶

The tuple of strategies owned by this meta-strategy.

Type: Tuple[Strategy]

__init__(*args)¶

Initialise a MetaStrategy instance.

Raises: TypeError – If an argument is not an instance of Strategy

descriptions() → Iterator[galactic.descriptions.Description]

Get an iterator over the descriptions.

Returns
Return type: Iterator[Description]

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

The selectors() method must return an iterator or selectors.

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

class galactic.strategies.Measure¶

Bases: collections.abc.Callable

The Measure class is an abstract class. Its subclasses must implement the __call__() method.

abstract __call__(concept: galactic.concepts.Concept, predicate: galactic.descriptions.Predicate = None) → float¶

The __call__() method evaluate the individuals present in the concept whose call to predicate is true.

Parameters: concept (Concept) – The concept for which individuals will be tested.
Keyword Arguments: predicate (Predicate) – The predicate to be tested.
Returns: The computed measure.
Return type: float

class galactic.strategies.Filter(*args, measure: galactic.strategies.Measure = None, **kwargs)¶

Bases: galactic.strategies.MetaStrategy

The Filter class is a meta-strategy whose goal is to filter possible predecessor using a measure on the concept and its predecessor.

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

Bases: galactic.strategies.Filter

The LimitFilter class limits the possible predecessors by choosing those whose measure is greater (or less than a threshold).

__init__(*args, limit: SupportsFloat = 0.0, strict: bool = False, lower: bool = True, **kwargs)¶

Initialize a LimitFilter class.

Keyword Arguments

limit (SupportsFloat) – The limit value
strict (bool) – Is the limit strict?
lower (bool) – Is it a lower limit?

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

The selectors() method must return an iterator or selectors.

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

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

Bases: galactic.strategies.Filter

The SelectionFilter class limits the possible predecessors by choosing those whose measure is among the greatest (or smallest).

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.