Feature

Feature module holds base implementation for features, Feature, which creative agents have in their rule sets considering artifacts.

class creamas.rules.feature.Feature(name, domains, rtype)

Base feature class that is callable after initialization.

Each feature takes as an input an artifact, and returns feature’s value for that artifact. If artifact type is not supported, feature’s evaluation should return None.

Returned feature values can be of any type, but rules (Rule) should have appropriate mappers to map possible feature values to the interval [-1, 1].

Usage example:

from myfeat import MyFeature
from myartifact import MyArtifact
myart = MyArtifact(*myparams)
myart.domain = mytype
f = MyFeature()
mytype in f.domains == True # True
ret = f(myart)
type(ret) == f.rtype # True

Parameters

• name (str) – Feature’s name

• domains (list) – A list of all artifact domains (type) that can be evaluated with the feature.

• rtype – Value type returned by this feature. This can be combined with mappers accepting this type as the input parameter.

extract(artifact, **kwargs)

Extract feature’s value from an artifact.

If artifact with a domain not in domains is used as a parameter, the function should return None.

Returns

Value extracted from the artifact.

Return type

rtype or None

property domains

Set of acceptable artifact domains for this feature.

When artifacts with other domains are used as parameters for extract(), the function should return None.

property name

Human readable name of the feature.

property rtype

Value type returned by this feature.