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如何使用少样本示例

先决条件

本指南假设您熟悉以下概念

在本指南中,我们将学习如何创建一个简单的提示模板,该模板在生成时为模型提供示例输入和输出。为 LLM 提供一些这样的示例称为少样本学习,这是一种简单而强大的方法来指导生成,并且在某些情况下可以显著提高模型性能。

少样本提示模板可以从一组示例或从负责从定义的集合中选择示例子集的示例选择器类构建。

本指南将介绍使用字符串提示模板进行少样本学习。有关为聊天模型使用聊天消息进行少样本学习的指南,请参阅此处

为少样本示例创建格式化程序

配置一个格式化器,将少样本示例格式化为字符串。此格式化器应为 PromptTemplate 对象。

from langchain_core.prompts import PromptTemplate

example_prompt = PromptTemplate.from_template("Question: {question}\n{answer}")
API 参考:PromptTemplate

创建示例集

接下来,我们将创建一个少样本示例的列表。每个示例都应该是一个字典,表示上述定义的格式化提示的示例输入。

examples = [
{
"question": "Who lived longer, Muhammad Ali or Alan Turing?",
"answer": """
Are follow up questions needed here: Yes.
Follow up: How old was Muhammad Ali when he died?
Intermediate answer: Muhammad Ali was 74 years old when he died.
Follow up: How old was Alan Turing when he died?
Intermediate answer: Alan Turing was 41 years old when he died.
So the final answer is: Muhammad Ali
""",
},
{
"question": "When was the founder of craigslist born?",
"answer": """
Are follow up questions needed here: Yes.
Follow up: Who was the founder of craigslist?
Intermediate answer: Craigslist was founded by Craig Newmark.
Follow up: When was Craig Newmark born?
Intermediate answer: Craig Newmark was born on December 6, 1952.
So the final answer is: December 6, 1952
""",
},
{
"question": "Who was the maternal grandfather of George Washington?",
"answer": """
Are follow up questions needed here: Yes.
Follow up: Who was the mother of George Washington?
Intermediate answer: The mother of George Washington was Mary Ball Washington.
Follow up: Who was the father of Mary Ball Washington?
Intermediate answer: The father of Mary Ball Washington was Joseph Ball.
So the final answer is: Joseph Ball
""",
},
{
"question": "Are both the directors of Jaws and Casino Royale from the same country?",
"answer": """
Are follow up questions needed here: Yes.
Follow up: Who is the director of Jaws?
Intermediate Answer: The director of Jaws is Steven Spielberg.
Follow up: Where is Steven Spielberg from?
Intermediate Answer: The United States.
Follow up: Who is the director of Casino Royale?
Intermediate Answer: The director of Casino Royale is Martin Campbell.
Follow up: Where is Martin Campbell from?
Intermediate Answer: New Zealand.
So the final answer is: No
""",
},
]

让我们用一个示例测试一下格式化提示

print(example_prompt.invoke(examples[0]).to_string())
Question: Who lived longer, Muhammad Ali or Alan Turing?

Are follow up questions needed here: Yes.
Follow up: How old was Muhammad Ali when he died?
Intermediate answer: Muhammad Ali was 74 years old when he died.
Follow up: How old was Alan Turing when he died?
Intermediate answer: Alan Turing was 41 years old when he died.
So the final answer is: Muhammad Ali

将示例和格式化器传递给 FewShotPromptTemplate

最后,创建一个 FewShotPromptTemplate 对象。此对象接收少样本示例和少样本示例的格式化器。当此 FewShotPromptTemplate 被格式化时,它会使用 example_prompt 格式化传递的示例,然后将它们添加到最终提示的 suffix 之前

from langchain_core.prompts import FewShotPromptTemplate

prompt = FewShotPromptTemplate(
examples=examples,
example_prompt=example_prompt,
suffix="Question: {input}",
input_variables=["input"],
)

print(
prompt.invoke({"input": "Who was the father of Mary Ball Washington?"}).to_string()
)
Question: Who lived longer, Muhammad Ali or Alan Turing?

Are follow up questions needed here: Yes.
Follow up: How old was Muhammad Ali when he died?
Intermediate answer: Muhammad Ali was 74 years old when he died.
Follow up: How old was Alan Turing when he died?
Intermediate answer: Alan Turing was 41 years old when he died.
So the final answer is: Muhammad Ali


Question: When was the founder of craigslist born?

Are follow up questions needed here: Yes.
Follow up: Who was the founder of craigslist?
Intermediate answer: Craigslist was founded by Craig Newmark.
Follow up: When was Craig Newmark born?
Intermediate answer: Craig Newmark was born on December 6, 1952.
So the final answer is: December 6, 1952


Question: Who was the maternal grandfather of George Washington?

Are follow up questions needed here: Yes.
Follow up: Who was the mother of George Washington?
Intermediate answer: The mother of George Washington was Mary Ball Washington.
Follow up: Who was the father of Mary Ball Washington?
Intermediate answer: The father of Mary Ball Washington was Joseph Ball.
So the final answer is: Joseph Ball


Question: Are both the directors of Jaws and Casino Royale from the same country?

Are follow up questions needed here: Yes.
Follow up: Who is the director of Jaws?
Intermediate Answer: The director of Jaws is Steven Spielberg.
Follow up: Where is Steven Spielberg from?
Intermediate Answer: The United States.
Follow up: Who is the director of Casino Royale?
Intermediate Answer: The director of Casino Royale is Martin Campbell.
Follow up: Where is Martin Campbell from?
Intermediate Answer: New Zealand.
So the final answer is: No


Question: Who was the father of Mary Ball Washington?

通过向模型提供这样的示例,我们可以引导模型给出更好的响应。

使用示例选择器

我们将重用上一节的示例集和格式化器。但是,我们不是将示例直接输入到 FewShotPromptTemplate 对象中,而是将它们输入到名为 SemanticSimilarityExampleSelector 实例的 ExampleSelector 实现中。此类根据与输入的相似性从初始集中选择少样本示例。它使用嵌入模型计算输入和少样本示例之间的相似性,并使用向量存储执行最近邻搜索。

为了展示它的外观,让我们初始化一个实例并单独调用它

from langchain_chroma import Chroma
from langchain_core.example_selectors import SemanticSimilarityExampleSelector
from langchain_openai import OpenAIEmbeddings

example_selector = SemanticSimilarityExampleSelector.from_examples(
# This is the list of examples available to select from.
examples,
# This is the embedding class used to produce embeddings which are used to measure semantic similarity.
OpenAIEmbeddings(),
# This is the VectorStore class that is used to store the embeddings and do a similarity search over.
Chroma,
# This is the number of examples to produce.
k=1,
)

# Select the most similar example to the input.
question = "Who was the father of Mary Ball Washington?"
selected_examples = example_selector.select_examples({"question": question})
print(f"Examples most similar to the input: {question}")
for example in selected_examples:
print("\n")
for k, v in example.items():
print(f"{k}: {v}")
Examples most similar to the input: Who was the father of Mary Ball Washington?


answer:
Are follow up questions needed here: Yes.
Follow up: Who was the mother of George Washington?
Intermediate answer: The mother of George Washington was Mary Ball Washington.
Follow up: Who was the father of Mary Ball Washington?
Intermediate answer: The father of Mary Ball Washington was Joseph Ball.
So the final answer is: Joseph Ball

question: Who was the maternal grandfather of George Washington?

现在,让我们创建一个 FewShotPromptTemplate 对象。此对象接收示例选择器和少样本示例的格式化提示。

prompt = FewShotPromptTemplate(
example_selector=example_selector,
example_prompt=example_prompt,
suffix="Question: {input}",
input_variables=["input"],
)

print(
prompt.invoke({"input": "Who was the father of Mary Ball Washington?"}).to_string()
)
Question: Who was the maternal grandfather of George Washington?

Are follow up questions needed here: Yes.
Follow up: Who was the mother of George Washington?
Intermediate answer: The mother of George Washington was Mary Ball Washington.
Follow up: Who was the father of Mary Ball Washington?
Intermediate answer: The father of Mary Ball Washington was Joseph Ball.
So the final answer is: Joseph Ball


Question: Who was the father of Mary Ball Washington?

下一步

您现在已经学会了如何将少样本示例添加到提示中。

接下来,查看本节中关于提示模板的其他操作指南、关于使用聊天模型进行少样本学习的相关操作指南,或者其他示例选择器操作指南


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