PDF

PDF Processing Guide

Overview

This guide covers essential PDF processing operations using Python libraries and command-line tools. For advanced features, JavaScript libraries, and detailed examples, see reference.md. If you need to fill out a PDF form, read forms.md and follow its instructions.

Quick Start

from pypdf import PdfReader, PdfWriter

# Read a PDF
reader = PdfReader("document.pdf")
print(f"Pages: {len(reader.pages)}")

# Extract text
text = ""
for page in reader.pages:
    text += page.extract_text()

Python Libraries

pypdf - Basic Operations

Merge PDFs

from pypdf import PdfWriter, PdfReader

writer = PdfWriter()
for pdf_file in ["doc1.pdf", "doc2.pdf", "doc3.pdf"]:
    reader = PdfReader(pdf_file)
    for page in reader.pages:
        writer.add_page(page)

with open("merged.pdf", "wb") as output:
    writer.write(output)

Split PDF

reader = PdfReader("input.pdf")
for i, page in enumerate(reader.pages):
    writer = PdfWriter()
    writer.add_page(page)
    with open(f"page_{i+1}.pdf", "wb") as output:
        writer.write(output)

Extract Metadata

reader = PdfReader("document.pdf")
meta = reader.metadata
print(f"Title: {meta.title}")
print(f"Author: {meta.author}")
print(f"Subject: {meta.subject}")
print(f"Creator: {meta.creator}")

Rotate Pages

reader = PdfReader("input.pdf")
writer = PdfWriter()

page = reader.pages[0]
page.rotate(90)  # Rotate 90 degrees clockwise
writer.add_page(page)

with open("rotated.pdf", "wb") as output:
    writer.write(output)

pdfplumber - Text and Table Extraction

Extract Text with Layout

import pdfplumber

with pdfplumber.open("document.pdf") as pdf:
    for page in pdf.pages:
        text = page.extract_text()
        print(text)

Extract Tables

with pdfplumber.open("document.pdf") as pdf:
    for i, page in enumerate(pdf.pages):
        tables = page.extract_tables()
        for j, table in enumerate(tables):
            print(f"Table {j+1} on page {i+1}:")
            for row in table:
                print(row)

Advanced Table Extraction

import pandas as pd

with pdfplumber.open("document.pdf") as pdf:
    all_tables = []
    for page in pdf.pages:
        tables = page.extract_tables()
        for table in tables:
            if table:  # Check if table is not empty
                df = pd.DataFrame(table[1:], columns=table[0])
                all_tables.append(df)

# Combine all tables
if all_tables:
    combined_df = pd.concat(all_tables, ignore_index=True)
    combined_df.to_excel("extracted_tables.xlsx", index=False)

reportlab - Create PDFs

Basic PDF Creation

from reportlab.lib.pagesizes import letter
from reportlab.pdfgen import canvas

c = canvas.Canvas("hello.pdf", pagesize=letter)
width, height = letter

# Add text
c.drawString(100, height - 100, "Hello World!")
c.drawString(100, height - 120, "This is a PDF created with reportlab")

# Add a line
c.line(100, height - 140, 400, height - 140)

# Save
c.save()

Create PDF with Multiple Pages

from reportlab.lib.pagesizes import letter
from reportlab.platypus import SimpleDocTemplate, Paragraph, Spacer, PageBreak
from reportlab.lib.styles import getSampleStyleSheet

doc = SimpleDocTemplate("report.pdf", pagesize=letter)
styles = getSampleStyleSheet()
story = []

# Add content
title = Paragraph("Report Title", styles['Title'])
story.append(title)
story.append(Spacer(1, 12))

body = Paragraph("This is the body of the report. " * 20, styles['Normal'])
story.append(body)
story.append(PageBreak())

# Page 2
story.append(Paragraph("Page 2", styles['Heading1']))
story.append(Paragraph("Content for page 2", styles['Normal']))

# Build PDF
doc.build(story)

支持中文

from reportlab.lib.pagesizes import letter
from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
from reportlab.platypus import Paragraph, SimpleDocTemplate, Spacer
from reportlab.pdfbase import pdfmetrics
from reportlab.pdfbase.ttfonts import TTFont
from reportlab.lib.enums import TA_LEFT
import os

# 尝试多个可能的字体路径
font_candidates = [
    '/System/Library/Fonts/PingFang.ttc',
    '/System/Library/Fonts/Supplemental/Songti.ttc',
    '/System/Library/Fonts/Supplemental/STSong.ttf',
    '/System/Library/Fonts/Supplemental/Kaiti.ttc',
    '/System/Library/Fonts/Supplemental/Arial Unicode.ttf',
    '/Library/Fonts/Arial Unicode.ttf',
]

font_registered = False
for font_path in font_candidates:
    if os.path.exists(font_path):
        try:
            pdfmetrics.registerFont(TTFont('ChineseFont', font_path))
            print(f"✓ 成功加载字体: {font_path}")
            font_registered = True
            break
        except Exception as e:
            print(f"✗ 尝试加载 {font_path} 失败: {e}")

if not font_registered:
    print("\n❌ 未找到可用字体，请运行字体查找代码")
    print("或手动指定字体路径")
    exit(1)

# Create PDF
doc = SimpleDocTemplate("红腹锦鸡保护报告.pdf", pagesize=letter)
styles = getSampleStyleSheet()

# 创建支持中文的样式
styles.add(ParagraphStyle(
    name='ChineseTitle', 
    fontName='ChineseFont', 
    fontSize=24, 
    leading=30,
    alignment=TA_LEFT
))

styles.add(ParagraphStyle(
    name='ChineseHeading', 
    fontName='ChineseFont', 
    fontSize=16, 
    leading=20
))

styles.add(ParagraphStyle(
    name='ChineseNormal', 
    fontName='ChineseFont', 
    fontSize=12, 
    leading=18
))

story = []

# Title
story.append(Paragraph("红腹锦鸡保护报告", styles['ChineseTitle']))
story.append(Spacer(1, 12))

# 1. 红腹锦鸡的基本介绍
story.append(Paragraph("1. 红腹锦鸡的基本介绍", styles['ChineseHeading']))
story.append(Paragraph("红腹锦鸡（学名：Chrysolophus pictus），又名金鸡，是一种美丽的鸟类，属于雉科。雄性红腹锦鸡羽毛鲜艳，头部有金黄色羽冠，颈部和胸部呈橙红色，背部为绿色，尾羽长而华丽。雌性则较为朴素，全身以褐色为主，便于隐蔽。红腹锦鸡主要分布于中国中部和西南部山区，栖息于海拔1000-2500米的森林和灌木丛中。", styles['ChineseNormal']))
story.append(Spacer(1, 12))

# 2. 现存种群数量
story.append(Paragraph("2. 现存种群数量", styles['ChineseHeading']))
story.append(Paragraph("根据近年来的调查数据，红腹锦鸡的野生种群数量约为10,000至20,000只。由于栖息地破坏和非法捕猎，种群数量呈下降趋势。", styles['ChineseNormal']))
story.append(Spacer(1, 12))

# 3. 保护现状
story.append(Paragraph("3. 保护现状", styles['ChineseHeading']))
story.append(Paragraph("红腹锦鸡被列为中国国家一级保护动物，并被列入《世界自然保护联盟》（IUCN）濒危物种红色名录中的'近危'（NT）等级。中国已建立多个自然保护区，如四川卧龙自然保护区、贵州梵净山自然保护区等，以保护红腹锦鸡及其栖息地。", styles['ChineseNormal']))
story.append(Spacer(1, 12))

# 4. 繁殖生物学特性
story.append(Paragraph("4. 繁殖生物学特性", styles['ChineseHeading']))
story.append(Paragraph("红腹锦鸡的繁殖期为每年4月至6月。雄性通过展示华丽的羽毛和舞蹈来吸引雌性。雌性每次产卵4-8枚，孵化期约为22-24天。雏鸟为早成鸟，出生后不久即可跟随母鸟活动。", styles['ChineseNormal']))
story.append(Spacer(1, 12))

# 5. 主要威胁因素
story.append(Paragraph("5. 主要威胁因素", styles['ChineseHeading']))
story.append(Paragraph("红腹锦鸡面临的主要威胁包括：<br/>- 栖息地破坏：森林砍伐和农业开发导致栖息地减少。<br/>- 非法捕猎：因其羽毛美丽，常被非法捕猎用于装饰或贸易。<br/>- 气候变化：气候变化可能影响其栖息环境和食物来源。", styles['ChineseNormal']))

# Build PDF
doc.build(story)
print("\n✓ PDF 生成成功！")

Command-Line Tools

pdftotext (poppler-utils)

# Extract text
pdftotext input.pdf output.txt

# Extract text preserving layout
pdftotext -layout input.pdf output.txt

# Extract specific pages
pdftotext -f 1 -l 5 input.pdf output.txt  # Pages 1-5

qpdf

# Merge PDFs
qpdf --empty --pages file1.pdf file2.pdf -- merged.pdf

# Split pages
qpdf input.pdf --pages . 1-5 -- pages1-5.pdf
qpdf input.pdf --pages . 6-10 -- pages6-10.pdf

# Rotate pages
qpdf input.pdf output.pdf --rotate=+90:1  # Rotate page 1 by 90 degrees

# Remove password
qpdf --password=mypassword --decrypt encrypted.pdf decrypted.pdf

pdftk (if available)

# Merge
pdftk file1.pdf file2.pdf cat output merged.pdf

# Split
pdftk input.pdf burst

# Rotate
pdftk input.pdf rotate 1east output rotated.pdf

Common Tasks

Extract Text from Scanned PDFs

# Requires: pip install pytesseract pdf2image
import pytesseract
from pdf2image import convert_from_path

# Convert PDF to images
images = convert_from_path('scanned.pdf')

# OCR each page
text = ""
for i, image in enumerate(images):
    text += f"Page {i+1}:\n"
    text += pytesseract.image_to_string(image)
    text += "\n\n"

print(text)

Add Watermark

from pypdf import PdfReader, PdfWriter

# Create watermark (or load existing)
watermark = PdfReader("watermark.pdf").pages[0]

# Apply to all pages
reader = PdfReader("document.pdf")
writer = PdfWriter()

for page in reader.pages:
    page.merge_page(watermark)
    writer.add_page(page)

with open("watermarked.pdf", "wb") as output:
    writer.write(output)

Extract Images

# Using pdfimages (poppler-utils)
pdfimages -j input.pdf output_prefix

# This extracts all images as output_prefix-000.jpg, output_prefix-001.jpg, etc.

Password Protection

from pypdf import PdfReader, PdfWriter

reader = PdfReader("input.pdf")
writer = PdfWriter()

for page in reader.pages:
    writer.add_page(page)

# Add password
writer.encrypt("userpassword", "ownerpassword")

with open("encrypted.pdf", "wb") as output:
    writer.write(output)

Quick Reference

Next Steps

• For advanced pypdfium2 usage, see reference.md
• For JavaScript libraries (pdf-lib), see reference.md
• If you need to fill out a PDF form, follow the instructions in forms.md
• For troubleshooting guides, see reference.md