SoFunction
Updated on 2025-04-14

Detailed tutorial on using PDF parsing tool pdfplumber in Python

1. Introduction and installation

1.1 pdfplumber overview

pdfplumber is a Python library designed for extracting text, tables and other information from PDF files. Compared with other PDF processing libraries, pdfplumber provides a more intuitive API and more precise text positioning capabilities.

Main features:

  • Extract text accurately (including location, font and other information)
  • Efficient extraction of table data
  • Supports page-level and document-level operations
  • Visual debugging function

1.2 Installation method

pip install pdfplumber

1.3 Basic usage examples

import pdfplumber

with ("") as pdf:
    first_page = [0]
    print(first_page.extract_text())

Code explanation:

  • ()Open PDF file
  • Get a list of all pages
  • extract_text() extracts page text content

2. Text extraction function

2.1 Basic text extraction

with ("") as pdf:
    for page in :
        print(page.extract_text())

Application scenarios: contract text analysis, report content extraction, etc.

2.2 Text extraction in format

with ("") as pdf:
    page = [0]
    words = page.extract_words()
    for word in words:
        print(f"text: {word['text']}, Location: {word['x0'], word['top']}, Font: {word['fontname']}")

Output example:

Text: Title, Location: (72.0, 84.0), Font: Helvetica-Bold
Text: Content, Location: (72.0, 96.0), Font: Helvetica

2.3 Extract text by region

with ("") as pdf:
    page = [0]
    # Define the area (x0, top, x1, bottom)    area = (50, 100, 400, 300)  
    cropped = (area)
    print(cropped.extract_text())

Application scenario: Extract specific information from invoices, key data from scanned documents, etc.

3. Table extraction function

3.1 Simple form extraction

with ("") as pdf:
    page = [0]
    table = page.extract_table()
    for row in table:
        print(row)

Output example:

['Name', 'Age', 'Occupation']
['Zhang San', '28', 'Engineer']
['Li Si', '32', 'Designer']

3.2 Complex table processing

with ("complex_table.pdf") as pdf:
    page = [0]
    # Customize table settings    table_settings = {
        "vertical_strategy": "text", 
        "horizontal_strategy": "text",
        "intersection_y_tolerance": 10
    }
    table = page.extract_table(table_settings)

Parameter description:

  • vertical_strategy: vertical segmentation strategy
  • horizontal_strategy: horizontal segmentation strategy
  • interference_y_tolerance: row merge tolerance

3.3 Multi-page table processing

with ("multi_page_table.pdf") as pdf:
    full_table = []
    for page in :
        table = page.extract_table()
        if table:
            # Skip the table header (assuming that there is already a table header on the first page)            if page.page_number > 1:
                table = table[1:]
            full_table.extend(table)
    
    for row in full_table:
        print(row)

Application scenarios: financial statement analysis, data report summary, etc.

4. Advanced features

4.1 Visual debugging

with ("") as pdf:
    page = [0]
    im = page.to_image()
    im.debug_tablefinder().show()

Function description:

  • to_image() converts the page into an image
  • debug_tablefinder() highlights the detected table
  • show() displays the image (Pillow is required)

4.2 Extracting graphic elements

with ("") as pdf:
    page = [0]
    lines = 
    curves = 
    rects = 
    
    print(f"turn up {len(lines)} A straight line")
    print(f"turn up {len(curves)} Curve")
    print(f"turn up {len(rects)} Rectangles")

Application scenarios: engineering drawing analysis, design document processing, etc.

4.3 Custom extraction strategy

def custom_extract_method(page):
    # Get all character objects    chars = 
    # Group by y coordinate (row)    lines = {}
    for char in chars:
        line_key = round(char["top"])
        if line_key not in lines:
            lines[line_key] = []
        lines[line_key].append(char)
    
    # Sort by x coordinates and splice text    result = []
    for y in sorted(()):
        line_chars = sorted(lines[y], key=lambda c: c["x0"])
        line_text = "".join([c["text"] for c in line_chars])
        (line_text)
    
    return "\n".join(result)

​​​​​​​with ("") as pdf:
    page = [0]
    print(custom_extract_method(page))

Application scenario: Handling PDF documents in special formats

5. Performance optimization skills

5.1 Loading the page on demand

with ("") as pdf:
    # Only process the first 5 pages    for page in [:5]:
        process(page.extract_text())

5.2 Parallel processing

from  import ThreadPoolExecutor

def process_page(page):
    return page.extract_text()

with ("big_file.pdf") as pdf:
    with ThreadPoolExecutor(max_workers=4) as executor:
        results = list((process_page, ))

5.3 Cache processing results

import pickle

def extract_and_cache(pdf_path, cache_path):
    try:
        with open(cache_path, "rb") as f:
            return (f)
    except FileNotFoundError:
        with (pdf_path) as pdf:
            data = [page.extract_text() for page in ]
            with open(cache_path, "wb") as f:
                (data, f)
            return data

text_data = extract_and_cache("", "report_cache.pkl")

6. Practical application cases

6.1 Invoice information extraction system

def extract_invoice_info(pdf_path):
    invoice_data = {
        "invoice_no": None,
        "date": None,
        "total": None
    }
    
    with (pdf_path) as pdf:
        for page in :
            text = page.extract_text()
            lines = ("\n")
            
            for line in lines:
                if "Invoice number" in line:
                    invoice_data["invoice_no"] = (":")[1].strip()
                elif "date" in line:
                    invoice_data["date"] = (":")[1].strip()
                elif "total" in line:
                    invoice_data["total"] = ()[-1]
    
    return invoice_data

6.2 Academic paper analysis

def analyze_paper(pdf_path):
    sections = {
        "abstract": "",
        "introduction": "",
        "conclusion": ""
    }
    
    with (pdf_path) as pdf:
        current_section = None
        for page in :
            text = page.extract_text()
            for line in ("\n"):
                line = ()
                if () == "abstract":
                    current_section = "abstract"
                elif ().startswith("1. introduction"):
                    current_section = "introduction"
                elif ().startswith("conclusion"):
                    current_section = "conclusion"
                elif current_section:
                    sections[current_section] += line + "\n"
    
    return sections

6.3 Financial statement conversion

import csv

def convert_pdf_to_csv(pdf_path, csv_path):
    with (pdf_path) as pdf:
        with open(csv_path, "w", newline="") as f:
            writer = (f)
            for page in :
                table = page.extract_table()
                if table:
                    (table)

7. FAQs and Solutions

7.1 Chinese garbled problem

with ("") as pdf:
    page = [0]
    # Make sure the system has Chinese fonts installed    text = page.extract_text()
    print(("utf-8").decode("utf-8"))

Solution:

  • Make sure the system has the correct fonts installed
  • Check Python environment encoding settings
  • Use PDF parser parameters that support Chinese

7.2 Inaccurate form identification

table_settings = {
    "vertical_strategy": "lines",
    "horizontal_strategy": "lines",
    "explicit_vertical_lines": ,
    "explicit_horizontal_lines": ,
    "intersection_x_tolerance": 15,
    "intersection_y_tolerance": 15
}
table = page.extract_table(table_settings)

Adjust strategy:

  • Try different segmentation strategies
  • Adjust tolerance parameters
  • Use the Visual Debugging Tool

7.3 Large file processing insufficient memory

# Process page by page and release memory immediatelywith ("") as pdf:
    for i, page in enumerate():
        process(page.extract_text())
        # Manually release page resources        pdf.release_resources()
        if i % 10 == 0:
            print(f"Processed {i+1} Page")

8. Summary and Best Practices

8.1 pdfplumber core advantages

  • Precise text positioning: preserve the location information of the text in the page
  • Powerful table extraction: outstanding ability to handle complex table structures
  • Rich metadata: Provide format information such as font, size, etc.
  • Visual debugging: intuitive verification of parsing results
  • Flexible API: Supports custom extraction logic

8.2 Recommended applicable scenarios

Preferred pdfplumber:

  • Applications that require precise text location information
  • Complex PDF table data extraction
  • Scenarios that need to be analyzed for PDF format and typesetting

Consider other options:

  • Just simple text extraction (PyPDF2 can be considered)
  • Need to edit PDF (consider PyMuPDF)
  • Extra large PDF file processing (consider paging processing)

8.3 Best Practice Recommendations

Preprocessing PDF files:

# Optimize PDF using Ghostscriptimport subprocess
(["gs", "-sDEVICE=pdfwrite", "-dNOPAUSE", "-dBATCH", 
               "-dSAFER", "-sOutputFile=", ""])

Use multiple tools in combination:

# Combine PyMuPDF to get more accurate text locationimport fitz
doc = ("")

Establish an error handling mechanism:

def safe_extract(pdf_path):
    try:
        with (pdf_path) as pdf:
            return [0].extract_text()
    except Exception as e:
        print(f"deal with{pdf_path}An error occurred while: {str(e)}")
        return None

Performance monitoring:

import time
start = ()
# pdf processing operationsprint(f"Time-consuming processing: {()-start:.2f}Second")

pdfplumber is one of the most powerful PDF parsing libraries in the Python ecosystem, and is especially suitable for application scenarios that require precise extraction of text and tabular data. Most PDF processing needs can be solved by rationally using its rich features and flexible APIs. For special needs, combining other PDF processing tools and custom logic, an efficient and reliable PDF processing process can be built.

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