Pdf Processing

PDF Processing

Quick start

Use pdfplumber to extract text from PDFs:

import pdfplumber

with pdfplumber.open("document.pdf") as pdf:
    text = pdf.pages[0].extract_text()
    print(text)

Extracting tables

Extract tables from PDFs with automatic detection:

import pdfplumber

with pdfplumber.open("report.pdf") as pdf:
    page = pdf.pages[0]
    tables = page.extract_tables()

    for table in tables:
        for row in table:
            print(row)

Extracting all pages

Process multi-page documents efficiently:

import pdfplumber

with pdfplumber.open("document.pdf") as pdf:
    full_text = ""
    for page in pdf.pages:
        full_text += page.extract_text() + "\n\n"

    print(full_text)

Form filling

For PDF form filling, see FORMS.md for the complete guide including field analysis and validation.

Merging PDFs

Combine multiple PDF files:

from pypdf import PdfMerger

merger = PdfMerger()

for pdf in ["file1.pdf", "file2.pdf", "file3.pdf"]:
    merger.append(pdf)

merger.write("merged.pdf")
merger.close()

Splitting PDFs

Extract specific pages or ranges:

from pypdf import PdfReader, PdfWriter

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

# Extract pages 2-5
for page_num in range(1, 5):
    writer.add_page(reader.pages[page_num])

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

Available packages

• pdfplumber - Text and table extraction (recommended)
• pypdf - PDF manipulation, merging, splitting
• pdf2image - Convert PDFs to images (requires poppler)
• pytesseract - OCR for scanned PDFs (requires tesseract)

Common patterns

Extract and save text:

import pdfplumber

with pdfplumber.open("input.pdf") as pdf:
    text = "\n\n".join(page.extract_text() for page in pdf.pages)

with open("output.txt", "w") as f:
    f.write(text)

Extract tables to CSV:

import pdfplumber
import csv

with pdfplumber.open("tables.pdf") as pdf:
    tables = pdf.pages[0].extract_tables()

    with open("output.csv", "w", newline="") as f:
        writer = csv.writer(f)
        for table in tables:
            writer.writerows(table)

Error handling

Handle common PDF issues:

import pdfplumber

try:
    with pdfplumber.open("document.pdf") as pdf:
        if len(pdf.pages) == 0:
            print("PDF has no pages")
        else:
            text = pdf.pages[0].extract_text()
            if text is None or text.strip() == "":
                print("Page contains no extractable text (might be scanned)")
            else:
                print(text)
except Exception as e:
    print(f"Error processing PDF: {e}")

Performance tips

• Process pages in batches for large PDFs
• Use multiprocessing for multiple files
• Extract only needed pages rather than entire document
• Close PDF objects after use

PDF Form Filling Guide

Overview

This guide covers filling PDF forms programmatically using PyPDF2 and pdfrw libraries.

Analyzing form fields

First, identify all fillable fields in a PDF:

from pypdf import PdfReader

reader = PdfReader("form.pdf")
fields = reader.get_fields()

for field_name, field_info in fields.items():
    print(f"Field: {field_name}")
    print(f"  Type: {field_info.get('/FT')}")
    print(f"  Value: {field_info.get('/V')}")
    print()

Filling form fields

Fill fields with values:

from pypdf import PdfReader, PdfWriter

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

writer.append_pages_from_reader(reader)

# Fill form fields
writer.update_page_form_field_values(
    writer.pages[0],
    {
        "name": "John Doe",
        "email": "john@example.com",
        "address": "123 Main St"
    }
)

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

Flattening forms

Remove form fields after filling (make non-editable):

from pypdf import PdfReader, PdfWriter

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

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

# Flatten all form fields
writer.flatten_form_fields()

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

Validation

Validate field values before filling:

def validate_email(email):
    return "@" in email and "." in email

def validate_form_data(data, required_fields):
    errors = []

    for field in required_fields:
        if field not in data or not data[field]:
            errors.append(f"Missing required field: {field}")

    if "email" in data and not validate_email(data["email"]):
        errors.append("Invalid email format")

    return errors

# Usage
data = {"name": "John Doe", "email": "john@example.com"}
required = ["name", "email", "address"]

errors = validate_form_data(data, required)
if errors:
    print("Validation errors:")
    for error in errors:
        print(f"  - {error}")
else:
    # Proceed with filling
    pass

Common field types

Text fields:

writer.update_page_form_field_values(
    writer.pages[0],
    {"text_field": "Some text"}
)

Checkboxes:

# Check a checkbox
writer.update_page_form_field_values(
    writer.pages[0],
    {"checkbox_field": "/Yes"}
)

# Uncheck a checkbox
writer.update_page_form_field_values(
    writer.pages[0],
    {"checkbox_field": "/Off"}
)

Radio buttons:

writer.update_page_form_field_values(
    writer.pages[0],
    {"radio_group": "/Option1"}
)

Best practices

1. Always validate input data before filling 2. Check field names match exactly (case-sensitive) 3. Test with small files first 4. Keep originals - work on copies 5. Flatten after filling for distribution