rasa 以知识图谱为基础的action

ゝ一世哀愁。 2022-10-12 01:28 249阅读 0赞

本文翻译自：https://rasa.com/docs/action-server/knowledge-bases  
仅供学习参考。

1、为什么要引入知识图谱？

答曰：在对话中，用户的输入并不总是某些对象的名字，而是用第几个或者它之类的引用话术，那么我们就需要跟踪这些对象信息，以便解析为用户所理解的正确对象；

并且用户还可能希望在对话中获得对象的详细的信息，比如《黑客帝国》的主演有谁？那么由于对象的信息非常多变，如果采取硬编码工程量太大，所以rasa提供了集成知识库来应对此挑战；

要使用此集成，可以创建从ActionQueryKnowledgeBase继承的自定义操作。

2、创建一个knowledge Base

一开始为了熟悉，我将先使用InMemoryKnowledgeBase，这个是什么意思？就是知识库是在内存中，还不是存储在数据库中，当数据量非常大的时候才创建（后续再研究）；

那么为了初始化InMemoryKnowledgeBase，我们需要有一个json文件，下面为示例，下面的json包含了三个餐厅和三个酒店的信息，restaurant里面的是键值对，每个同级的对象都应该包含相同的键值对，其中id和name是必要的，如果你不想要，则必须要去修改InMemoryKnowledgeBase

{ 
        "restaurant": [
            { 
                "id": 0,
                "name": "Donath",
                "cuisine": "Italian",
                "outside-seating": true,
                "price-range": "mid-range"
            },
            { 
                "id": 1,
                "name": "Berlin Burrito Company",
                "cuisine": "Mexican",
                "outside-seating": false,
                "price-range": "cheap"
            },
            { 
                "id": 2,
                "name": "I due forni",
                "cuisine": "Italian",
                "outside-seating": true,
                "price-range": "mid-range"
            }
        ],
        "hotel": [
            { 
                "id": 0,
                "name": "Hilton",
                "price-range": "expensive",
                "breakfast-included": true,
                "city": "Berlin",
                "free-wifi": true,
                "star-rating": 5,
                "swimming-pool": true
            },
            { 
                "id": 1,
                "name": "Hilton",
                "price-range": "expensive",
                "breakfast-included": true,
                "city": "Frankfurt am Main",
                "free-wifi": true,
                "star-rating": 4,
                "swimming-pool": false
            },
            { 
                "id": 2,
                "name": "B&B",
                "price-range": "mid-range",
                "breakfast-included": false,
                "city": "Berlin",
                "free-wifi": false,
                "star-rating": 1,
                "swimming-pool": false
            },
        ]
    }

3、定义NLU

新意图：query\_knowledge\_base，为了让bot知道用户希望从知识库中进行检索；  
对提及的实体进行注释，以便模型能够检测到类似于“第一个”这样的引用话术；  
广泛的使用同义词。  
ActionQueryKnowledgeBase可以处理两种请求：

查询特定类型的对象列表，回到上面的例子就是查询有多少restaurant，那么将会返回一个列表；  
查询某个对象的特定属性，这就是更细的查询了，比如查询restaurant里面Donath的cuisine；

那么意图应该包含这两种请求的多种变式。

- intent: query_knowledge_base
      examples: |
        - what [restaurants]{ "entity": "object_type", "value": "restaurant"} can you recommend?
        - list some [restaurants]{ "entity": "object_type", "value": "restaurant"}
        - can you name some [restaurants]{ "entity": "object_type", "value": "restaurant"} please?
        - can you show me some [restaurant]{ "entity": "object_type", "value": "restaurant"} options
        - list [German]{ "entity": "cuisine"} [restaurants]{ "entity": "object_type", "value": "restaurant"}
        - do you have any [mexican]{ "entity": "cuisine"} [restaurants]{ "entity": "object_type", "value": "restaurant"}?
        - do you know the [price range]{ "entity": "attribute", "value": "price-range"} of [that one]{ "entity": "mention"}?
        - what [cuisine]{ "entity": "attribute"} is [it]{ "entity": "mention"}?
        - do you know what [cuisine]{ "entity": "attribute"} the [last one]{ "entity": "mention", "value": "LAST"} has?
        - does [Donath]{ "entity": "restaurant"} have [outside seating]{ "entity": "attribute", "value": "outside-seating"}?
        - what is the [price range]{ "entity": "attribute", "value": "price-range"} of [Berlin Burrito Company]{ "entity": "restaurant"}?
        - what is with [I due forni]{ "entity": "restaurant"}?
        - Do you also have any [Vietnamese]{ "entity": "cuisine"} [restaurants]{ "entity": "object_type", "value": "restaurant"}?
        - What about any [Mexican]{ "entity": "cuisine", "value": "mexican"} [restaurants]{ "entity": "object_type", "value": "restaurant"}?
        - Do you also know some [Italian]{ "entity": "cuisine"} [restaurants]{ "entity": "object_type", "value": "restaurant"}?
        - can you tell me the [price range]{ "entity": "attribute", "value": "price-range"} of [that restaurant]{ "entity": "mention"}?
        - what [cuisine]{ "entity": "attribute"} do [they]{ "entity": "mention"} have?
        - what [hotels]{ "entity": "object_type", "value": "hotel"} can you recommend?
        - please list some [hotels]{ "entity": "object_type", "value": "hotel"} in [Frankfurt am Main]{ "entity": "city"} for me
        - what [hotels]{ "entity": "object_type", "value": "hotel"} do you know in [Berlin]{ "entity": "city"}?
        - name some [hotels]{ "entity": "object_type", "value": "hotel"} in [Berlin]{ "entity": "city"}
        - show me some [hotels]{ "entity": "object_type", "value": "hotel"}
        - what are [hotels]{ "entity": "object_type", "value": "hotel"} in [Berlin]{ "entity": "city"}
        - does the [last]{ "entity": "mention", "value": "LAST"} one offer [breakfast]{ "entity": "attribute", "value": "breakfast-included"}?
        - does the [second one]{ "entity": "mention", "value": "2"} [include breakfast]{ "entity": "attribute", "value": "breakfast-included"}?
        - what is the [price range]{ "entity": "attribute", "value": "price-range"} of the [second]{ "entity": "mention", "value": "2"} hotel?
        - does the [first]{ "entity": "mention", "value": "1"} one have [wifi]{ "entity": "attribute", "value": "free-wifi"}?
        - does the [third]{ "entity": "mention", "value": "3"} one have a [swimming pool]{ "entity": "attribute", "value": "swimming-pool"}?
        - what is the [star rating]{ "entity": "attribute", "value": "star-rating"} of [Berlin Wall Hostel]{ "entity": "hotel"}?
        - Does the [Hilton]{ "entity": "hotel"} have a [swimming pool]{ "entity": "attribute", "value": "swimming-pool"}?

要在nlu中指定和注释一下的实体：

object\_type （对象类型）：每当Nlu中引用知识库的特定对象类型，该对象类型应该标记为实体，如 restaurant ，它是知识库里面的键；  
mention （提及，引用）：如果用户通过“第一个”、 “那个”、“它” 来引用对象，那么应该把这些属于标记为mention；  
attribute：在知识库中的所有属性在nlu中有应该标记为attribute，可以使用同义词将属性名称映射到知识库中的名称。

还需要在domain中增加这些实体：

entities:
      - object_type
      - mention
      - attribute
     
    slots:
      object_type:
        type: unfeaturized
      mention:
        type: unfeaturized
      attribute:
        type: unfeaturized

4、创建一个action去查询你的知识库

action.py
    from rasa_sdk.knowledge_base.storage import InMemoryKnowledgeBase
    from rasa_sdk.knowledge_base.actions import ActionQueryKnowledgeBase
     
    class MyKnowledgeBaseAction(ActionQueryKnowledgeBase):
        def __init__(self):
            knowledge_base = InMemoryKnowledgeBase("data.json")
            super().__init__(knowledge_base)

必须 要将知识库传递给构造的类，现在这样是InMemoryKnowledgeBase，当然也可以是自己的知识库，但是需要注意只能从一个知识库里面提取信息，暂时还不支持同时使用多个知识库。

不要忘记将此action加入到domain 中

domain.yml
    actions:
    - action_query_knowledge_base

5、查询知识库对象

为了能够查询任何知识库的对象，用户请求需要包含object\_type对象类型，来看下例子

用户：Can you please name some restaurants?

这个问题中包含了"restaruants"，bot需要获取这个实体以行程查询

用户：What Italian restaurant options in Berlin do I have?

这个问题中用户希望获得（1）有意大利料理（2）位于柏林的餐厅列表，那么NER在处理中将获得这些属性，然后通过这些属性去知识库中过滤找到对应的餐厅。

相应的需要在NLU中做配合

intents:
    - intent: query_knowledge_base
      examples: |
        - What [Italian](cuisine) [restaurant](object_type) options in [Berlin](city) do I have?.

这里的cuisine和city应该与知识库中的相对应，并讲这些作为实体和词槽加入domain里面。

6、查询知识库对象属性

这种查询用于用户希望查询有关对象的特定信息，那么该请求应该包含感兴趣的对象和属性，例如：

用户：What is the cuisine of Berlin Burrito Company?

其中cuisine（感兴趣的对象的属性） Berlin Burrito Company（感兴趣的对象）

NLU中也要有训练的数据

intents:
    - intent: query_knowledge_base
      examples: |
        - What is the [cuisine](attribute) of [Berlin Burrito Company](restaurant)?

7、解决引用话术的问题

按照上面的例子，用户有可能不是用具体的名字来指代餐馆，也可能提及引用先前列出的对象，比如：

用户：What is the cuisine of the second restaurant you mentioned?

rasa可以解析两种引用类型：（1）有序停用，如“第一个”，（2）例如“它”或者“那一个”。

8、有序引用

当用户根据对象在列表中的位置引用对象时，成为顺序引用，如：

User: What restaurants in Berlin do you know?

Bot: Found the following objects of type ‘restaurant’: 1: I due forni 2: PastaBar 3: Berlin Burrito Company

User: Does the first one have outside seating?

有序引用通常在向用户展示对象列表的时候使用，为了能够解析这些引用为实际对象，在KnowledgeBase里面设置了有序的引用映射, /rasa-sdk/knowledge\_base/storage.py

storage.py
    class KnowledgeBase:
        def __init__(self) -> None:
     
            self.ordinal_mention_mapping = { 
                "1": lambda l: l[0],
                "2": lambda l: l[1],
                "3": lambda l: l[2],
                "4": lambda l: l[3],
                "5": lambda l: l[4],
                "6": lambda l: l[5],
                "7": lambda l: l[6],
                "8": lambda l: l[7],
                "9": lambda l: l[8],
                "10": lambda l: l[9],
                "ANY": lambda l: random.choice(l),
                "LAST": lambda l: l[-1],
            }
        ....

如果提到“第一个”，那么可以在NLU中使用同义词来做映射

intents:
    - intent: query_knowledge_base
      examples: |
        - Does the [first one]{ entity: "mention", value": 1} have [outside seating]{entity: "attribute", value": "outside-seating"}

9、其他引用

看下面的一段对话

User: What is the cuisine of PastaBar?

Bot: PastaBar has an Italian cuisine.

User: Does it have wifi?

Bot: Yes.

User: Can you give me an address

如果NER检测到it， 那么知识库操作会将它解析为会话中最后提到的对象"PastaBar" 。