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这将帮助您开始使用 LangChain 的 Nomic 嵌入模型。有关 NomicEmbeddings 功能和配置选项的详细文档,请参阅API 参考

概览

集成详情

设置

要访问 Nomic 嵌入模型,您需要创建一个 Nomic 帐户,获取 API 密钥,并安装 langchain-nomic 集成包。

凭据

请前往https://atlas.nomic.ai/注册 Nomic 并生成 API 密钥。完成后,设置 NOMIC_API_KEY 环境变量。
import getpass
import os

if not os.getenv("NOMIC_API_KEY"):
    os.environ["NOMIC_API_KEY"] = getpass.getpass("Enter your Nomic API key: ")
要启用模型调用的自动化跟踪,请设置您的 LangSmith API 密钥
os.environ["LANGSMITH_TRACING"] = "true"
os.environ["LANGSMITH_API_KEY"] = getpass.getpass("Enter your LangSmith API key: ")

安装

LangChain Nomic 集成位于 langchain-nomic 包中。
pip install -qU langchain-nomic
Note: you may need to restart the kernel to use updated packages.

实例化

现在我们可以实例化我们的模型对象并生成聊天完成
from langchain_nomic import NomicEmbeddings

embeddings = NomicEmbeddings(
    model="nomic-embed-text-v1.5",
    # dimensionality=256,
    # Nomic's `nomic-embed-text-v1.5` model was [trained with Matryoshka learning](https://blog.nomic.ai/posts/nomic-embed-matryoshka)
    # to enable variable-length embeddings with a single model.
    # This means that you can specify the dimensionality of the embeddings at inference time.
    # The model supports dimensionality from 64 to 768.
    # inference_mode="remote",
    # One of `remote`, `local` (Embed4All), or `dynamic` (automatic). Defaults to `remote`.
    # api_key=... , # if using remote inference,
    # device="cpu",
    # The device to use for local embeddings. Choices include
    # `cpu`, `gpu`, `nvidia`, `amd`, or a specific device name. See
    # the docstring for `GPT4All.__init__` for more info. Typically
    # defaults to CPU. Do not use on macOS.
)

索引和检索

嵌入模型通常用于检索增强生成 (RAG) 流程,既作为数据索引的一部分,也用于后续检索数据。有关更详细的说明,请参阅我们的RAG 教程 下面,我们将演示如何使用我们上面初始化的 embeddings 对象来索引和检索数据。在此示例中,我们将在 InMemoryVectorStore 中索引和检索一个示例文档。
# Create a vector store with a sample text
from langchain_core.vectorstores import InMemoryVectorStore

text = "LangChain is the framework for building context-aware reasoning applications"

vectorstore = InMemoryVectorStore.from_texts(
    [text],
    embedding=embeddings,
)

# Use the vectorstore as a retriever
retriever = vectorstore.as_retriever()

# Retrieve the most similar text
retrieved_documents = retriever.invoke("What is LangChain?")

# show the retrieved document's content
retrieved_documents[0].page_content
'LangChain is the framework for building context-aware reasoning applications'

直接使用

在底层,向量存储和检索器实现正在调用 embeddings.embed_documents(...)embeddings.embed_query(...) 分别为 from_texts 和检索 invoke 操作中使用的文本创建嵌入。 您可以直接调用这些方法来为自己的用例获取嵌入。

嵌入单个文本

您可以使用 embed_query 嵌入单个文本或文档
single_vector = embeddings.embed_query(text)
print(str(single_vector)[:100])  # Show the first 100 characters of the vector
[0.024642944, 0.029083252, -0.14013672, -0.09082031, 0.058898926, -0.07489014, -0.0138168335, 0.0037

嵌入多个文本

您可以使用 embed_documents 嵌入多个文本
text2 = (
    "LangGraph is a library for building stateful, multi-actor applications with LLMs"
)
two_vectors = embeddings.embed_documents([text, text2])
for vector in two_vectors:
    print(str(vector)[:100])  # Show the first 100 characters of the vector
[0.012771606, 0.023727417, -0.12365723, -0.083740234, 0.06530762, -0.07110596, -0.021896362, -0.0068
[-0.019058228, 0.04058838, -0.15222168, -0.06842041, -0.012130737, -0.07128906, -0.04534912, 0.00522

API 参考

有关 NomicEmbeddings 功能和配置选项的详细文档,请参阅API 参考
以编程方式连接这些文档到 Claude、VSCode 等,通过 MCP 获取实时答案。
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