使用Owlready访问本体实体注解属性（如definition）报错的解决方法

需求：使用Owlready库读取HumanDO.owl本体中实体的注解属性，例如获取「冲动控制障碍」的definition属性。

原测试代码：

from owlready2 import *
onto = get_ontology("./HumanDO.owl").load()
for subclass_of_mental_health in list(onto.search(label ="disease of mental health")[0].subclasses()):
    print(subclass_of_mental_health.id, subclass_of_mental_health.label) # 可正常输出
    print(subclass_of_mental_health.definition) # 执行报错

报错信息：

['DOID:10937'] ['impulse control disorder']
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
~\AppData\Local\Temp\ipykernel_14348\3127299132.py in <module>
      1 for subclass_of_mental_health in list(onto.search(label ="disease of mental health")[0].subclasses()):
      2     print(subclass_of_mental_health.id, subclass_of_mental_health.label)
----> 3     print(subclass_of_mental_health.definition)

E:\Python\PythonInstall\envs\new\lib\site-packages\owlready2\entity.py in __getattr__(Class, attr)
    592     else:
    593       Prop = Class.namespace.world._props.get(attr)
--> 594       if not Prop: raise AttributeError("'%s' property is not defined." % attr)
    595       if issubclass_python(Prop, AnnotationProperty):
    596         attr = "__%s" % attr # Do NOT cache as such in __dict__, to avoid inheriting annotations

AttributeError: 'definition' property is not defined.

当前仅能通过点标记访问id和label属性，其他注解属性无法直接访问，卡在读取环节。

问题原因 #

Owlready中，id和label是库预定义的常用属性，可直接通过点访问；但像definition这类本体自定义的注解属性，需要先明确对应的AnnotationProperty对象，或使用通用方法获取注解内容。

解决方案 #

HumanDO本体中，definition对应的是IAO_0000115这个标准注解属性，以下两种方法可获取其值：

方法1：使用get_annotation方法获取注解 #

通过实体的get_annotation方法，传入对应的注解属性对象来获取值：

from owlready2 import *
onto = get_ontology("./HumanDO.owl").load()

# 获取definition对应的注解属性对象
definition_prop = onto.get_annotation_property("http://purl.obolibrary.org/obo/IAO_0000115")

# 遍历子类并读取definition
mental_health_disease = onto.search(label ="disease of mental health")[0]
for subclass in list(mental_health_disease.subclasses()):
    print(subclass.id, subclass.label)
    # 获取并打印definition注解值
    definition = subclass.get_annotation(definition_prop)
    print(definition)

方法2：通过属性IRI直接访问 #

如果本体已绑定前缀，可直接通过前缀+属性名访问；未绑定则需使用完整IRI：

from owlready2 import *
onto = get_ontology("./HumanDO.owl").load()

# 遍历子类并读取definition（使用完整IRI）
mental_health_disease = onto.search(label ="disease of mental health")[0]
for subclass in list(mental_health_disease.subclasses()):
    print(subclass.id, subclass.label)
    # 通过完整IRI访问注解属性
    print(subclass["http://purl.obolibrary.org/obo/IAO_0000115"])

额外说明 #

若不确定目标注解属性的IRI，可通过onto.annotation_properties()列出本体中所有注解属性，从中查找对应属性的IRI信息。

内容的提问来源于stack exchange，提问作者ASLAN