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本指南提供了 PyMuPDF4LLM 文档加载器 的快速入门概述。有关 PyMuPDF4LLMLoader 所有特性和配置的详细文档,请参阅 GitHub 仓库

概述

集成详情

本地可序列化JS 支持
PyMuPDF4LLMLoaderlangchain-pymupdf4llm

加载器特性

来源文档惰性加载原生异步支持提取图片提取表格
PyMuPDF4LLMLoader

设置

要访问 PyMuPDF4LLM 文档加载器,需要安装 langchain-pymupdf4llm 集成包。

凭据

使用 PyMuPDF4LLMLoader 无需任何凭据。 若要启用模型调用的自动追踪,请设置您的 LangSmith API 密钥:
os.environ["LANGSMITH_API_KEY"] = getpass.getpass("Enter your LangSmith API key: ")
os.environ["LANGSMITH_TRACING"] = "true"

安装

安装 langchain-communitylangchain-pymupdf4llm
pip install -qU langchain-community langchain-pymupdf4llm

初始化

现在我们可以实例化模型对象并加载文档:
from langchain_pymupdf4llm import PyMuPDF4LLMLoader

file_path = "./example_data/layout-parser-paper.pdf"
loader = PyMuPDF4LLMLoader(file_path)

加载

docs = loader.load()
docs[0]
Document(metadata={'producer': 'pdfTeX-1.40.21', 'creator': 'LaTeX with hyperref', 'creationdate': '2021-06-22T01:27:10+00:00', 'source': './example_data/layout-parser-paper.pdf', 'file_path': './example_data/layout-parser-paper.pdf', 'total_pages': 16, 'format': 'PDF 1.5', 'title': '', 'author': '', 'subject': '', 'keywords': '', 'moddate': '2021-06-22T01:27:10+00:00', 'trapped': '', 'modDate': 'D:20210622012710Z', 'creationDate': 'D:20210622012710Z', 'page': 0}, page_content='\`\`\`\nLayoutParser: A Unified Toolkit for Deep\n\n## Learning Based Document Image Analysis\n\n\`\`\`\n\nZejiang Shen[1] (\ufffd), Ruochen Zhang[2], Melissa Dell[3], Benjamin Charles Germain\nLee[4], Jacob Carlson[3], and Weining Li[5]\n\n1 Allen Institute for AI\n\`\`\`\n              shannons@allenai.org\n\n\`\`\`\n2 Brown University\n\`\`\`\n             ruochen zhang@brown.edu\n\n\`\`\`\n3 Harvard University\n_{melissadell,jacob carlson}@fas.harvard.edu_\n4 University of Washington\n\`\`\`\n              bcgl@cs.washington.edu\n\n\`\`\`\n5 University of Waterloo\n\`\`\`\n              w422li@uwaterloo.ca\n\n\`\`\`\n\n**Abstract. Recent advances in document image analysis (DIA) have been**\nprimarily driven by the application of neural networks. Ideally, research\noutcomes could be easily deployed in production and extended for further\ninvestigation. However, various factors like loosely organized codebases\nand sophisticated model configurations complicate the easy reuse of important innovations by a wide audience. Though there have been on-going\nefforts to improve reusability and simplify deep learning (DL) model\ndevelopment in disciplines like natural language processing and computer\nvision, none of them are optimized for challenges in the domain of DIA.\nThis represents a major gap in the existing toolkit, as DIA is central to\nacademic research across a wide range of disciplines in the social sciences\nand humanities. This paper introduces LayoutParser, an open-source\nlibrary for streamlining the usage of DL in DIA research and applications. The core LayoutParser library comes with a set of simple and\nintuitive interfaces for applying and customizing DL models for layout detection, character recognition, and many other document processing tasks.\nTo promote extensibility, LayoutParser also incorporates a community\nplatform for sharing both pre-trained models and full document digitization pipelines. We demonstrate that LayoutParser is helpful for both\nlightweight and large-scale digitization pipelines in real-word use cases.\n[The library is publicly available at https://layout-parser.github.io.](https://layout-parser.github.io)\n\n**Keywords: Document Image Analysis · Deep Learning · Layout Analysis**\n\n    - Character Recognition · Open Source library · Toolkit.\n\n### 1 Introduction\n\n\nDeep Learning(DL)-based approaches are the state-of-the-art for a wide range of\ndocument image analysis (DIA) tasks including document image classification [11,\n\n')
import pprint

pprint.pp(docs[0].metadata)
{'producer': 'pdfTeX-1.40.21',
 'creator': 'LaTeX with hyperref',
 'creationdate': '2021-06-22T01:27:10+00:00',
 'source': './example_data/layout-parser-paper.pdf',
 'file_path': './example_data/layout-parser-paper.pdf',
 'total_pages': 16,
 'format': 'PDF 1.5',
 'title': '',
 'author': '',
 'subject': '',
 'keywords': '',
 'moddate': '2021-06-22T01:27:10+00:00',
 'trapped': '',
 'modDate': 'D:20210622012710Z',
 'creationDate': 'D:20210622012710Z',
 'page': 0}

惰性加载

pages = []
for doc in loader.lazy_load():
    pages.append(doc)
    if len(pages) >= 10:
        # do some paged operation, e.g.
        # index.upsert(page)

        pages = []
len(pages)
6
from IPython.display import Markdown, display

part = pages[0].page_content[778:1189]
print(part)
# Markdown rendering
display(Markdown(part))
pprint.pp(pages[0].metadata)
{'producer': 'pdfTeX-1.40.21',
 'creator': 'LaTeX with hyperref',
 'creationdate': '2021-06-22T01:27:10+00:00',
 'source': './example_data/layout-parser-paper.pdf',
 'file_path': './example_data/layout-parser-paper.pdf',
 'total_pages': 16,
 'format': 'PDF 1.5',
 'title': '',
 'author': '',
 'subject': '',
 'keywords': '',
 'moddate': '2021-06-22T01:27:10+00:00',
 'trapped': '',
 'modDate': 'D:20210622012710Z',
 'creationDate': 'D:20210622012710Z',
 'page': 10}
metadata 属性至少包含以下键:
  • source
  • page(如果处于 page 模式)
  • total_page
  • creationdate
  • creator
  • producer
其他元数据因解析器而异。 这些信息可以提供帮助(例如,用于对 PDF 进行分类)。

分割模式与自定义页面分隔符

加载 PDF 文件时,可以通过以下两种方式进行分割:
  • 按页分割
  • 作为单一文本流
默认情况下,PyMuPDF4LLMLoader 将按页分割 PDF。

按页提取 PDF——每页作为一个 LangChain 文档对象提取

loader = PyMuPDF4LLMLoader(
    "./example_data/layout-parser-paper.pdf",
    mode="page",
)
docs = loader.load()

print(len(docs))
pprint.pp(docs[0].metadata)
16
{'producer': 'pdfTeX-1.40.21',
 'creator': 'LaTeX with hyperref',
 'creationdate': '2021-06-22T01:27:10+00:00',
 'source': './example_data/layout-parser-paper.pdf',
 'file_path': './example_data/layout-parser-paper.pdf',
 'total_pages': 16,
 'format': 'PDF 1.5',
 'title': '',
 'author': '',
 'subject': '',
 'keywords': '',
 'moddate': '2021-06-22T01:27:10+00:00',
 'trapped': '',
 'modDate': 'D:20210622012710Z',
 'creationDate': 'D:20210622012710Z',
 'page': 0}
在此模式下,PDF 按页分割,生成的 Documents 元数据包含 page(页码)。但在某些情况下,我们可能希望将 PDF 作为单一文本流处理(避免段落被截断)。此时可以使用 single 模式:

将整个 PDF 作为单一 LangChain 文档对象提取

loader = PyMuPDF4LLMLoader(
    "./example_data/layout-parser-paper.pdf",
    mode="single",
)
docs = loader.load()

print(len(docs))
pprint.pp(docs[0].metadata)
1
{'producer': 'pdfTeX-1.40.21',
 'creator': 'LaTeX with hyperref',
 'creationdate': '2021-06-22T01:27:10+00:00',
 'source': './example_data/layout-parser-paper.pdf',
 'file_path': './example_data/layout-parser-paper.pdf',
 'total_pages': 16,
 'format': 'PDF 1.5',
 'title': '',
 'author': '',
 'subject': '',
 'keywords': '',
 'moddate': '2021-06-22T01:27:10+00:00',
 'trapped': '',
 'modDate': 'D:20210622012710Z',
 'creationDate': 'D:20210622012710Z'}
从逻辑上说,在此模式下,page(page_number)元数据会消失。以下是如何在文本流中清晰标识页面结束位置的方法:

single 模式下添加自定义 pages_delimiter 以标识页面结束位置

loader = PyMuPDF4LLMLoader(
    "./example_data/layout-parser-paper.pdf",
    mode="single",
    pages_delimiter="\n-------THIS IS A CUSTOM END OF PAGE-------\n\n",
)
docs = loader.load()

part = docs[0].page_content[10663:11317]
print(part)
display(Markdown(part))
默认的 pages_delimiter 是 \n-----\n\n。 但这也可以简单地是 \n,或 \f 以清晰表示页面切换,或者使用 <!— PAGE BREAK —> 在 Markdown 查看器中无缝注入而不产生视觉效果。

从 PDF 中提取图片

您可以从 PDF 中提取图片(以文本形式),可选择以下三种方案之一:
  • rapidOCR(轻量级光学字符识别工具)
  • Tesseract(高精度 OCR 工具)
  • 多模态语言模型
结果将插入到页面文本末尾。

使用 rapidOCR 从 PDF 中提取图片

pip install -qU rapidocr-onnxruntime pillow
from langchain_community.document_loaders.parsers import RapidOCRBlobParser

loader = PyMuPDF4LLMLoader(
    "./example_data/layout-parser-paper.pdf",
    mode="page",
    extract_images=True,
    images_parser=RapidOCRBlobParser(),
)
docs = loader.load()

part = docs[5].page_content[1863:]
print(part)
display(Markdown(part))
注意,RapidOCR 专为中文和英文设计,不适用于其他语言。

使用 tesseract 从 PDF 中提取图片

pip install -qU pytesseract
from langchain_community.document_loaders.parsers import TesseractBlobParser

loader = PyMuPDF4LLMLoader(
    "./example_data/layout-parser-paper.pdf",
    mode="page",
    extract_images=True,
    images_parser=TesseractBlobParser(),
)
docs = loader.load()

print(docs[5].page_content[1863:])

使用多模态模型从 PDF 中提取图片

pip install -qU langchain-openai
import os

from dotenv import load_dotenv

load_dotenv()
True
from getpass import getpass

if not os.environ.get("OPENAI_API_KEY"):
    os.environ["OPENAI_API_KEY"] = getpass("OpenAI API key =")
from langchain_community.document_loaders.parsers import LLMImageBlobParser
from langchain_openai import ChatOpenAI

loader = PyMuPDF4LLMLoader(
    "./example_data/layout-parser-paper.pdf",
    mode="page",
    extract_images=True,
    images_parser=LLMImageBlobParser(
        model=ChatOpenAI(model="gpt-4.1-mini", max_tokens=1024)
    ),
)
docs = loader.load()

print(docs[5].page_content[1863:])

从 PDF 中提取表格

使用 PyMUPDF4LLM,您可以将 PDF 中的表格提取为 markdown 格式:
loader = PyMuPDF4LLMLoader(
    "./example_data/layout-parser-paper.pdf",
    mode="page",
    # "lines_strict" is the default strategy and
    # is the most accurate for tables with column and row lines,
    # but may not work well with all documents.
    # "lines" is a less strict strategy that may work better with
    # some documents.
    # "text" is the least strict strategy and may work better
    # with documents that do not have tables with lines.
    table_strategy="lines",
)
docs = loader.load()

part = docs[4].page_content[3210:]
print(part)
display(Markdown(part))

处理文件

许多文档加载器涉及文件解析。此类加载器之间的差异通常在于文件的解析方式,而非加载方式。例如,您可以使用 open 读取 PDF 或 Markdown 文件的二进制内容,但需要不同的解析逻辑将二进制数据转换为文本。 因此,将解析逻辑与加载逻辑解耦会很有帮助,这样无论数据如何加载,都可以更轻松地复用给定的解析器。 您可以使用此策略以相同的解析参数分析不同的文件。
from langchain_community.document_loaders import FileSystemBlobLoader
from langchain_community.document_loaders.generic import GenericLoader
from langchain_pymupdf4llm import PyMuPDF4LLMParser

loader = GenericLoader(
    blob_loader=FileSystemBlobLoader(
        path="./example_data/",
        glob="*.pdf",
    ),
    blob_parser=PyMuPDF4LLMParser(),
)
docs = loader.load()

part = docs[0].page_content[:562]
print(part)
display(Markdown(part))

API 参考

有关 PyMuPDF4LLMLoader 所有特性和配置的详细文档,请参阅 GitHub 仓库:github.com/lakinduboteju/langchain-pymupdf4llm