大型语言模型（LLMs）存在数据新鲜度问题。即使是像GPT-4这样最强大的模型，也不了解最近的事件。

根据LLMs的视角，世界仿佛停滞在某个时间点。它们只知道世界是如何在它们的训练数据中呈现的。

这对于依赖最新信息或特定数据集的任何用例都会带来问题。例如，您可能有一些内部公司文件，您希望通过LLM与之互动。

第一个挑战是将这些文件添加到LLM中，我们可以尝试训练LLM使用这些文件，但这是耗时且昂贵的。而且当添加新文件时会发生什么呢？为每个新文件进行训练是非常低效的，简直是不可能的。

那么，我们如何处理这个问题呢？我们可以使用检索增强技术。这种技术允许我们从外部知识库中检索相关信息，并将这些信息提供给我们的LLM。

外部知识库就是我们了解LLM训练数据之外世界的”窗口”。在本章中，我们将学习如何使用LangChain为LLMs实施检索增强。

创建知识库

我们有两种主要类型的知识适用于LLMs。参数化知识指的是LLM在训练过程中学到的一切，它充当了LLM的世界的冻结快照。

第二种类型的知识是源知识。这种知识包括通过输入提示输入到LLM中的任何信息。当我们谈论检索增强时，我们指的是向LLM提供有价值的源知识。

获取我们知识库的数据

为了帮助我们的LLM，我们需要为其提供访问相关源知识的能力。为了实现这一点，我们需要创建我们自己的知识库。

我们从一个数据集开始。所使用的数据集自然取决于用例。它可以是用于协助编写代码的代码文档，用于内部聊天机器人的公司文件，或者其他任何内容。

在我们的示例中，我们将使用维基百科的一个子集。为了获取这些数据，我们将使用Hugging Face数据集，如下所示：

In[2]:

kotlin
复制代码
from datasets import load_dataset

data = load_dataset("wikipedia", "20220301.simple", split='train[:10000]')
data

Out[2]:

ruby
复制代码
Downloading readme:   0%|          | 0.00/16.3k [00:00<?, ?B/s]

Out[2]:

php
复制代码
Dataset({
    features: ['id', 'url', 'title', 'text'],
    num_rows: 10000
})

In[3]:

css
复制代码
data[6]

Out[3]:

vbnet
复制代码
{'id': '13',
 'url': 'https://simple.wikipedia.org/wiki/Alan%20Turing',
 'title': 'Alan Turing',
 'text': 'Alan Mathison Turing OBE FRS (London, 23 June 1912 – Wilmslow, Cheshire, 7 June 1954) was an English mathematician and computer scientist. He was born in Maida Vale, London.nnEarly life and family nAlan Turing was born in Maida Vale, London on 23 June 1912. His father was part of a family of merchants from Scotland. His mother, Ethel Sara, was the daughter of an engineer.nnEducation nTuring went to St. Michael's, a school at 20 Charles Road, St Leonards-on-sea, when he was five years old.n"This is only a foretaste of what is to come, and only the shadow of what is going to be.” – Alan Turing.nnThe Stoney family were once prominent landlords, here in North Tipperary. His mother Ethel Sara Stoney (1881–1976) was daughter of Edward Waller Stoney (Borrisokane, North Tipperary) and Sarah Crawford (Cartron Abbey, Co. Longford); Protestant Anglo-Irish gentry.nnEducated in Dublin at Alexandra School and College; on October 1st 1907 she married Julius Mathison Turing, latter son of Reverend John Robert Turing and Fanny Boyd, in Dublin. Born on June 23rd 1912, Alan Turing would go on to be regarded as one of the greatest figures of the twentieth century.nnA brilliant mathematician and cryptographer Alan was to become the founder of modern-day computer science and artificial intelligence; designing a machine at Bletchley Park to break secret Enigma encrypted messages used by the Nazi German war machine to protect sensitive commercial, diplomatic and military communications during World War 2. Thus, Turing made the single biggest contribution to the Allied victory in the war against Nazi Germany, possibly saving the lives of an estimated 2 million people, through his effort in shortening World War II.nnIn 2013, almost 60 years later, Turing received a posthumous Royal Pardon from Queen Elizabeth II. Today, the “Turing law” grants an automatic pardon to men who died before the law came into force, making it possible for living convicted gay men to seek pardons for offences now no longer on the statute book.nnAlas, Turing accidentally or otherwise lost his life in 1954, having been subjected by a British court to chemical castration, thus avoiding a custodial sentence. He is known to have ended his life at the age of 41 years, by eating an apple laced with cyanide.nnCareer nTuring was one of the people who worked on the first computers. He created the theoretical  Turing machine in 1936. The machine was imaginary, but it included the idea of a computer program.nnTuring was interested in artificial intelligence. He proposed the Turing test, to say when a machine could be called "intelligent". A computer could be said to "think" if a human talking with it could not tell it was a machine.nnDuring World War II, Turing worked with others to break German ciphers (secret messages). He  worked for the Government Code and Cypher School (GC&CS) at Bletchley Park, Britain's codebreaking centre that produced Ultra intelligence.nUsing cryptanalysis, he helped to break the codes of the Enigma machine. After that, he worked on other German codes.nnFrom 1945 to 1947, Turing worked on the design of the ACE (Automatic Computing Engine) at the National Physical Laboratory. He presented a paper on 19 February 1946. That paper was "the first detailed design of a stored-program computer". Although it was possible to build ACE, there were delays in starting the project. In late 1947 he returned to Cambridge for a sabbatical year. While he was at Cambridge, the Pilot ACE was built without him. It ran its first program on 10xa0May 1950.nnPrivate life nTuring was a homosexual man. In 1952, he admitted having had sex with a man in England. At that time, homosexual acts were illegal. Turing was convicted. He had to choose between going to jail and taking hormones to lower his sex drive. He decided to take the hormones. After his punishment, he became impotent. He also grew breasts.nnIn May 2012, a private member's bill was put before the House of Lords to grant Turing a statutory pardon. In July 2013, the government supported it. A royal pardon was granted on 24 December 2013.nnDeath nIn 1954, Turing died from cyanide poisoning. The cyanide came from either an apple which was poisoned with cyanide, or from water that had cyanide in it. The reason for the confusion is that the police never tested the apple for cyanide. It is also suspected that he committed suicide.nnThe treatment forced on him is now believed to be very wrong. It is against medical ethics and international laws of human rights. In August 2009, a petition asking the British Government to apologise to Turing for punishing him for being a homosexual was started. The petition received thousands of signatures. Prime Minister Gordon Brown acknowledged the petition. He called Turing's treatment "appalling".nnReferencesnnOther websites nJack Copeland 2012. Alan Turing: The codebreaker who saved 'millions of lives'. BBC News / Technology nnEnglish computer scientistsnEnglish LGBT peoplenEnglish mathematiciansnGay mennLGBT scientistsnScientists from LondonnSuicides by poisonnSuicides in the United Kingdomn1912 birthsn1954 deathsnOfficers of the Order of the British Empire'}

大多数数据集将包含包含大量文本的记录。因此，我们通常的第一个任务是构建一个预处理管道，将那些长文本分割成更简洁的块。

创建文本块

将我们的文本分割成较小的块对于多个原因至关重要。主要目的是：

• 提高“嵌入准确性” – 这将提高后续结果的相关性。

• 减少输入到我们LLM作为源知识的文本数量。限制输入可以提高LLM遵循指令的能力，降低生成成本，并帮助我们获得更快的响应。

• 为用户提供更精确的信息源，因为我们可以将信息源缩小到更小的文本块。

• 对于非常长的文本块，我们将超出嵌入或完成模型的最大上下文窗口。分割这些文本块使得将这些较长的文档添加到我们的知识库成为可能。

要创建这些块，首先需要一种测量文本长度的方法。LLMs不是按单词或字符测量文本的 – 它们是按“标记”来测量的。

标记通常是单词或子词的大小，不同的LLMs有不同的标记大小。标记本身是由标记器构建的。我们将使用gpt-3.5-turbo作为我们的完成模型，并且我们可以像这样初始化该模型的标记器：

ini
复制代码
import tiktoken  # !pip install tiktoken

tokenizer = tiktoken.get_encoding('p50k_base')

使用标记器，我们可以从纯文本创建标记并计算标记的数量。我们将把这个过程封装到一个名为tiktoken_len的函数中：

In[28]:

arduino
复制代码
# create the length function
def tiktoken_len(text):
    tokens = tokenizer.encode(
        text,
        disallowed_special=()
    )
    return len(tokens)

tiktoken_len("hello I am a chunk of text and using the tiktoken_len function "
             "we can find the length of this chunk of text in tokens")

Out[28]:

复制代码
28

有了我们的标记计数函数准备好后，我们可以初始化一个LangChain RecursiveCharacterTextSplitter对象。这个对象将允许我们将文本分割成不超过我们通过chunk_size参数指定的长度的块。

ini
复制代码
from langchain.text_splitter import RecursiveCharacterTextSplitter

text_splitter = RecursiveCharacterTextSplitter(
    chunk_size=400,
    chunk_overlap=20,
    length_function=tiktoken_len,
    separators=["nn", "n", " ", ""]
)

现在我们可以这样分割文本：

In[6]:

css
复制代码
chunks = text_splitter.split_text(data[6]['text'])[:3]
chunks

Out[6]:

vbnet
复制代码
['Alan Mathison Turing OBE FRS (London, 23 June 1912 – Wilmslow, Cheshire, 7 June 1954) was an English mathematician and computer scientist. He was born in Maida Vale, London.nnEarly life and family nAlan Turing was born in Maida Vale, London on 23 June 1912. His father was part of a family of merchants from Scotland. His mother, Ethel Sara, was the daughter of an engineer.nnEducation nTuring went to St. Michael's, a school at 20 Charles Road, St Leonards-on-sea, when he was five years old.n"This is only a foretaste of what is to come, and only the shadow of what is going to be.” – Alan Turing.nnThe Stoney family were once prominent landlords, here in North Tipperary. His mother Ethel Sara Stoney (1881–1976) was daughter of Edward Waller Stoney (Borrisokane, North Tipperary) and Sarah Crawford (Cartron Abbey, Co. Longford); Protestant Anglo-Irish gentry.nnEducated in Dublin at Alexandra School and College; on October 1st 1907 she married Julius Mathison Turing, latter son of Reverend John Robert Turing and Fanny Boyd, in Dublin. Born on June 23rd 1912, Alan Turing would go on to be regarded as one of the greatest figures of the twentieth century.nnA brilliant mathematician and cryptographer Alan was to become the founder of modern-day computer science and artificial intelligence; designing a machine at Bletchley Park to break secret Enigma encrypted messages used by the Nazi German war machine to protect sensitive commercial, diplomatic and military communications during World War 2. Thus, Turing made the single biggest contribution to the Allied victory in the war against Nazi Germany, possibly saving the lives of an estimated 2 million people, through his effort in shortening World War II.',
 'In 2013, almost 60 years later, Turing received a posthumous Royal Pardon from Queen Elizabeth II. Today, the “Turing law” grants an automatic pardon to men who died before the law came into force, making it possible for living convicted gay men to seek pardons for offences now no longer on the statute book.nnAlas, Turing accidentally or otherwise lost his life in 1954, having been subjected by a British court to chemical castration, thus avoiding a custodial sentence. He is known to have ended his life at the age of 41 years, by eating an apple laced with cyanide.nnCareer nTuring was one of the people who worked on the first computers. He created the theoretical  Turing machine in 1936. The machine was imaginary, but it included the idea of a computer program.nnTuring was interested in artificial intelligence. He proposed the Turing test, to say when a machine could be called "intelligent". A computer could be said to "think" if a human talking with it could not tell it was a machine.nnDuring World War II, Turing worked with others to break German ciphers (secret messages). He  worked for the Government Code and Cypher School (GC&CS) at Bletchley Park, Britain's codebreaking centre that produced Ultra intelligence.nUsing cryptanalysis, he helped to break the codes of the Enigma machine. After that, he worked on other German codes.',
 'From 1945 to 1947, Turing worked on the design of the ACE (Automatic Computing Engine) at the National Physical Laboratory. He presented a paper on 19 February 1946. That paper was "the first detailed design of a stored-program computer". Although it was possible to build ACE, there were delays in starting the project. In late 1947 he returned to Cambridge for a sabbatical year. While he was at Cambridge, the Pilot ACE was built without him. It ran its first program on 10xa0May 1950.nnPrivate life nTuring was a homosexual man. In 1952, he admitted having had sex with a man in England. At that time, homosexual acts were illegal. Turing was convicted. He had to choose between going to jail and taking hormones to lower his sex drive. He decided to take the hormones. After his punishment, he became impotent. He also grew breasts.nnIn May 2012, a private member's bill was put before the House of Lords to grant Turing a statutory pardon. In July 2013, the government supported it. A royal pardon was granted on 24 December 2013.nnDeath nIn 1954, Turing died from cyanide poisoning. The cyanide came from either an apple which was poisoned with cyanide, or from water that had cyanide in it. The reason for the confusion is that the police never tested the apple for cyanide. It is also suspected that he committed suicide.nnThe treatment forced on him is now believed to be very wrong. It is against medical ethics and international laws of human rights. In August 2009, a petition asking the British Government to apologise to Turing for punishing him for being a homosexual was started. The petition received thousands of signatures. Prime Minister Gordon Brown acknowledged the petition. He called Turing's treatment "appalling".nnReferencesnnOther websites nJack Copeland 2012. Alan Turing: The codebreaker who saved 'millions of lives'. BBC News / Technology']

这些块都没有超过我们之前设置的400块大小限制：

In[7]:

scss
复制代码
tiktoken_len(chunks[0]), tiktoken_len(chunks[1]), tiktoken_len(chunks[2])

Out[7]:

scss
复制代码
(397, 304, 399)

使用文本分割器，我们获得了适当大小的文本块。稍后在索引过程中，我们将使用这个功能。现在，让我们来看看嵌入。

创建嵌入

矢量嵌入对于检索LLM的相关上下文至关重要。我们将希望存储在我们的知识库中的文本块进行编码，将每个块编码成一个矢量嵌入。

这些嵌入可以充当每个文本块含义的“数值表示”。这是可能的，因为我们使用另一个已经学会将人类可读文本转化为AI可读嵌入的AI语言模型来创建这些嵌入。

然后，我们将这些嵌入存储在我们的矢量数据库中（稍后会详细介绍），并通过在矢量空间中计算嵌入之间的距离来找到具有相似含义的文本块。

我们将使用的嵌入模型是另一个OpenAI模型，称为text-embedding-ada-002。我们可以像这样通过LangChain初始化它：

ini
复制代码
from langchain.embeddings.openai import OpenAIEmbeddings

model_name = 'text-embedding-ada-002'

embed = OpenAIEmbeddings(
    document_model_name=model_name,
    query_model_name=model_name,
    openai_api_key=OPENAI_API_KEY
)

现在我们可以嵌入我们的文本：

In[10]:

scss
复制代码
texts = [    'this is the first chunk of text',    'then another second chunk of text is here']

res = embed.embed_documents(texts)
len(res), len(res[0])

Out[10]:

scss
复制代码
(2, 1536)

从这里，我们得到了两个嵌入，因为我们传入了两个文本块。每个嵌入都是一个1536维的向量。这个维度只是text-embedding-ada-002的输出维度。

有了这些，我们拥有了我们的数据集、文本分割器和嵌入模型。我们具备了开始构建知识库所需的一切。

向量数据库

矢量数据库是一种知识库类型，它允许我们扩展对数十亿条记录的相似嵌入的搜索，通过添加、更新或删除记录来管理我们的知识库，甚至可以执行诸如过滤等操作。

我们将使用Pinecone矢量数据库。要使用它，我们需要一个免费的API密钥。然后，我们可以像这样初始化我们的数据库索引：

ini
复制代码
import pinecone

index_name = 'langchain-retrieval-augmentation'

pinecone.init(
        api_key="YOUR_API_KEY",  # find api key in console at app.pinecone.io
        environment="YOUR_ENV"  # find next to api key in console
)

# we create a new index
pinecone.create_index(
        name=index_name,
        metric='dotproduct',
        dimension=len(res[0]) # 1536 dim of text-embedding-ada-002
)

然后，我们连接到新的索引：

In[12]:

diff
复制代码
index = pinecone.GRPCIndex(index_name)

index.describe_index_stats()

Out[12]:

yaml
复制代码
{'dimension': 1536,
 'index_fullness': 0.0,
 'namespaces': {},
 'total_vector_count': 0}

我们会看到新的Pinecone索引的total_vector_count为0，因为我们还没有添加任何向量。我们接下来的任务是完成这一步。

索引过程包括遍历我们希望添加到知识库中的数据，创建ID、嵌入和元数据，然后将它们添加到索引中。

我们可以分批进行此操作以加速过程。

ini
复制代码
from tqdm.auto import tqdm
from uuid import uuid4

batch_limit = 100

texts = []
metadatas = []

for i, record in enumerate(tqdm(data)):
    # first get metadata fields for this record
    metadata = {
        'wiki-id': str(record['id']),
        'source': record['url'],
        'title': record['title']
    }
    # now we create chunks from the record text
    record_texts = text_splitter.split_text(record['text'])
    # create individual metadata dicts for each chunk
    record_metadatas = [{
        "chunk": j, "text": text, **metadata
    } for j, text in enumerate(record_texts)]
    # append these to current batches
    texts.extend(record_texts)
    metadatas.extend(record_metadatas)
    # if we have reached the batch_limit we can add texts
    if len(texts) >= batch_limit:
        ids = [str(uuid4()) for _ in range(len(texts))]
        embeds = embed.embed_documents(texts)
        index.upsert(vectors=zip(ids, embeds, metadatas))
        texts = []
        metadatas = []

现在我们已经完成了索引。要检查索引中记录的数量，我们再次调用describe_index_stats：

In[14]:

diff
复制代码
index.describe_index_stats()

Out[14]:

bash
复制代码
{'dimension': 1536,
 'index_fullness': 0.1,
 'namespaces': {'': {'vector_count': 27437}},
 'total_vector_count': 27437}

我们的索引包含大约27,000条记录。正如之前提到的，我们可以将这个数量扩展到数十亿，但对于我们的示例来说，27,000足够了。

LangChain矢量存储和查询

我们独立于LangChain构建我们的索引。这是因为这是一个简单的过程，而且直接使用Pinecone客户端更快。然而，我们即将回到LangChain，所以我们应该通过LangChain库重新连接到我们的索引。

ini
复制代码
from langchain.vectorstores import Pinecone

text_field = "text"

# switch back to normal index for langchain
index = pinecone.Index(index_name)

vectorstore = Pinecone(
    index, embed.embed_query, text_field
)

我们可以使用相似性搜索方法直接进行查询，返回文本块，而无需LLM生成响应。

In[16]:

ini
复制代码
query = "who was Benito Mussolini?"

vectorstore.similarity_search(
    query,  # our search query
    k=3  # return 3 most relevant docs
)

Out[16]:

vbnet
复制代码
[Document(page_content='Benito Amilcare Andrea Mussolini KSMOM GCTE (29 July 1883 – 28 April 1945) was an Italian politician and journalist. He was also the Prime Minister of Italy from 1922 until 1943. He was the leader of the National Fascist Party.nnBiographynnEarly lifenBenito Mussolini was named after Benito Juarez, a Mexican opponent of the political power of the Roman Catholic Church, by his anticlerical (a person who opposes the political interference of the Roman Catholic Church in secular affairs) father. Mussolini's father was a blacksmith. Before being involved in politics, Mussolini was a newspaper editor (where he learned all his propaganda skills) and elementary school teacher.nnAt first, Mussolini was a socialist, but when he wanted Italy to join the First World War, he was thrown out of the socialist party. He 'invented' a new ideology, Fascism, much out of Nationalistxa0and Conservative views.nnRise to power and becoming dictatornIn 1922, he took power by having a large group of men, "Black Shirts," march on Rome and threaten to take over the government. King Vittorio Emanuele III gave in, allowed him to form a government, and made him prime minister. In the following five years, he gained power, and in 1927 created the OVRA, his personal secret police force. Using the agency to arrest, scare, or murder people against his regime, Mussolini was dictatorxa0of Italy by the end of 1927. Only the King and his own Fascist party could challenge his power.', lookup_str='', metadata={'chunk': 0.0, 'source': 'https://simple.wikipedia.org/wiki/Benito%20Mussolini', 'title': 'Benito Mussolini', 'wiki-id': '6754'}, lookup_index=0),
 Document(page_content='Fascism as practiced by MussolininMussolini's form of Fascism, "Italian Fascism"- unlike Nazism, the racist ideology that Adolf Hitler followed- was different and less destructive than Hitler's. Although a believer in the superiority of the Italian nation and national unity, Mussolini, unlike Hitler, is quoted "Race? It is a feeling, not a reality. Nothing will ever make me believe that biologically pure races can be shown to exist today".nnMussolini wanted Italy to become a new Roman Empire. In 1923, he attacked the island of Corfu, and in 1924, he occupied the city state of Fiume. In 1935, he attacked the African country Abyssinia (now called Ethiopia). His forces occupied it in 1936. Italy was thrown out of the League of Nations because of this aggression. In 1939, he occupied the country Albania. In 1936, Mussolini signed an alliance with Adolf Hitler, the dictator of Germany.nnFall from power and deathnIn 1940, he sent Italy into the Second World War on the side of the Axis countries. Mussolini attacked Greece, but he failed to conquer it. In 1943, the Allies landed in Southern Italy. The Fascist party and King Vittorio Emanuel III deposed Mussolini and put him in jail, but he was set free by the Germans, who made him ruler of the Italian Social Republic puppet state which was in a small part of Central Italy. When the war was almost over, Mussolini tried to escape to Switzerland with his mistress, Clara Petacci, but they were both captured and shot by partisans. Mussolini's dead body was hanged upside-down, together with his mistress and some of Mussolini's helpers, on a pole at a gas station in the village of Millan, which is near the border  between Italy and Switzerland.', lookup_str='', metadata={'chunk': 1.0, 'source': 'https://simple.wikipedia.org/wiki/Benito%20Mussolini', 'title': 'Benito Mussolini', 'wiki-id': '6754'}, lookup_index=0),
 Document(page_content='Fascist Italy nIn 1922, a new Italian government started. It was ruled by Benito Mussolini, the leader of Fascism in Italy. He became head of government and dictator, calling himself "Il Duce" (which means "leader" in Italian). He became friends with German dictator Adolf Hitler. Germany, Japan, and Italy became the Axis Powers. In 1940, they entered World War II together against France, Great Britain, and later the Soviet Union. During the war, Italy controlled most of the Mediterranean Sea.nnOn July 25, 1943, Mussolini was removed by the Great Council of Fascism. On September 8, 1943, Badoglio said that the war as an ally of Germany was ended. Italy started fighting as an ally of France and the UK, but Italian soldiers did not know whom to shoot. In Northern Italy, a movement called Resistenza started to fight against the German invaders. On April 25, 1945, much of Italy became free, while Mussolini tried to make a small Northern Italian fascist state called the Republic of Salò. The fascist state failed and Mussolini tried to flee to Switzerland and escape to Francoist Spain, but he was captured by Italian partisans. On 28 April 1945 Mussolini was executed by a partisan.nnAfter World War Two nnThe state became a republic on June 2, 1946. For the first time, women were able to vote. Italian people ended the Savoia dynasty and adopted a republic government.nnIn February 1947, Italy signed a peace treaty with the Allies. They lost all the colonies and some territorial areas (Istria and parts of Dalmatia).nnSince then Italy has joined NATO and the European Community (as a founding member). It is one of the seven biggest industrial economies in the world.nnTransportation nnThe railway network in Italy totals . It is the 17th longest in the world. High speed trains include ETR-class trains which travel at .', lookup_str='', metadata={'chunk': 5.0, 'source': 'https://simple.wikipedia.org/wiki/Italy', 'title': 'Italy', 'wiki-id': '363'}, lookup_index=0)]

所有这些都是相关的结果，告诉我们我们的系统的检索组件正在运行。下一步是将我们的LLM添加进来，以生成性地回答我们的问题，使用在这些检索到的上下文中提供的信息。

生成式问答

在生成式问答（GQA）中，我们将问题传递给LLM，但指示它基于从我们的知识库返回的信息来生成答案。我们可以在LangChain中轻松地使用RetrievalQA链来实现这一点。

ini
复制代码
from langchain.chat_models import ChatOpenAI
from langchain.chains import RetrievalQA

# completion llm
llm = ChatOpenAI(
    openai_api_key=OPENAI_API_KEY,
    model_name='gpt-3.5-turbo',
    temperature=0.0
)

qa = RetrievalQA.from_chain_type(
    llm=llm,
    chain_type="stuff",
    retriever=vectorstore.as_retriever()
)

让我们尝试一下之前的查询：

In[22]:

scss
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qa.run(query)

Out[22]:

vbnet
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'Benito Mussolini was an Italian politician and journalist who served as the Prime Minister of Italy from 1922 until 1943. He was the leader of the National Fascist Party and invented the ideology of Fascism. Mussolini was a dictator of Italy by the end of 1927, and his form of Fascism, "Italian Fascism," was different and less destructive than Hitler's Nazism. Mussolini wanted Italy to become a new Roman Empire and attacked several countries, including Abyssinia (now called Ethiopia) and Greece. He was removed from power in 1943 and was executed by Italian partisans in 1945.'

这次我们得到的响应是由我们的gpt-3.5-turbo LLM根据从我们的矢量数据库中检索到的信息生成的。

尽管如此，我们仍然无法完全防止模型生成令人信服但虚假的幻觉，这种情况可能会发生，而且不太可能完全消除这个问题。然而，我们可以采取更多措施来提高我们对提供的答案的信任度。

一个有效的方法是在响应中添加引用，让用户看到信息来源。我们可以使用稍微不同版本的RetrievalQA链，称为RetrievalQAWithSourcesChain，来实现这一点。

In[23]:

ini
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from langchain.chains import RetrievalQAWithSourcesChain

qa_with_sources = RetrievalQAWithSourcesChain.from_chain_type(
    llm=llm,
    chain_type="stuff",
    retriever=vectorstore.as_retriever()
)

In[24]:

scss
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qa_with_sources(query)

Out[24]:

vbnet
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{'question': 'who was Benito Mussolini?',
 'answer': 'Benito Mussolini was an Italian politician and journalist who was the Prime Minister of Italy from 1922 until 1943. He was the leader of the National Fascist Party and invented the ideology of Fascism. He became dictator of Italy by the end of 1927 and was friends with German dictator Adolf Hitler. Mussolini attacked Greece and failed to conquer it. He was removed by the Great Council of Fascism in 1943 and was executed by a partisan on April 28, 1945. After the war, several Neo-Fascist movements have had success in Italy, the most important being the Movimento Sociale Italiano. His granddaughter Alessandra Mussolini has outspoken views similar to Fascism. n',
 'sources': 'https://simple.wikipedia.org/wiki/Benito%20Mussolini, https://simple.wikipedia.org/wiki/Fascism'}

现在，我们不仅回答了提出的问题，还包括了LLM使用的这些信息的来源。

我们已经学会了通过使用矢量数据库作为我们的知识库来为大型语言模型提供源知识的基础。利用这一点，我们可以鼓励LLM的响应准确性，保持源知识的更新，并通过在每个答案中提供引用来提高对我们系统的信任。

我们已经看到LLM和知识库在大型产品中配对使用，例如必应的AI搜索、Google Bard和ChatGPT插件。毫无疑问，LLM的未来与高性能、可扩展和可靠的知识库紧密相连。