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 **references/reference.md**. If you need to fill out a PDF form, read **references/forms.md** and follow its instructions. ## Quick Start ```python 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 ```python 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 ```python 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 ```python 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 ```python 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 ```python import pdfplumber with pdfplumber.open("document.pdf") as pdf: for page in pdf.pages: text = page.extract_text() print(text) ``` #### Extract Tables ```python 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 ```python 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 ```python 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 ```python 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) ``` #### Subscripts and Superscripts **IMPORTANT**: Never use Unicode subscript/superscript characters (₀₁₂₃₄₅₆₇₈₉, ⁰¹²³⁴⁵⁶⁷⁸⁹) in ReportLab PDFs. The built-in fonts do not include these glyphs, causing them to render as solid black boxes. Instead, use ReportLab's XML markup tags in Paragraph objects: ```python from reportlab.platypus import Paragraph from reportlab.lib.styles import getSampleStyleSheet styles = getSampleStyleSheet() # Subscripts: use <sub> tag chemical = Paragraph("H<sub>2</sub>O", styles["Normal"]) # Superscripts: use <super> tag squared = Paragraph("x<super>2</super> + y<super>2</super>", styles["Normal"]) ``` For canvas-drawn text (not Paragraph objects), manually adjust font size and position rather than using Unicode subscripts/superscripts. ## Command-Line Tools ### pdftotext (poppler-utils) ```bash # 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 ```bash # 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) ```bash # 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 ```python # 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 ```python 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 ```bash # 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 ```python 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 | Task | Best Tool | Command/Code | |------|-----------|--------------| | Merge PDFs | pypdf | `writer.add_page(page)` | | Split PDFs | pypdf | One page per file | | Extract text | pdfplumber | `page.extract_text()` | | Extract tables | pdfplumber | `page.extract_tables()` | | Create PDFs | reportlab | Canvas or Platypus | | Command line merge | qpdf | `qpdf --empty --pages ...` | | OCR scanned PDFs | pytesseract | Convert to image first | | Fill PDF forms | pdf-lib or pypdf (see references/forms.md) | See references/forms.md | ## Next Steps - For advanced pypdfium2 usage, see **references/reference.md** - For JavaScript libraries (pdf-lib), see **references/reference.md** - If you need to fill out a PDF form, follow the instructions in **references/forms.md** - For troubleshooting guides, see **references/reference.md** ## Scripts | Script | Purpose | |--------|---------| | `check_bounding_boxes.py` | Verify form field positions match visual layout | | `check_bounding_boxes_test.py` | Unit tests for `check_bounding_boxes.py` (run with `uv run`) | | `check_fillable_fields.py` | Check if a PDF has fillable form fields | | `convert_pdf_to_images.py` | Convert PDF pages to images | | `extract_form_field_info.py` | Extract form field metadata from PDFs | | `extract_form_structure.py` | Extract form structure from non-fillable PDFs | | `fill_fillable_fields.py` | Fill fillable PDF form fields | | `fill_pdf_form_with_annotations.py` | Fill PDF forms using annotations | | `create_validation_image.py` | Optional: overlay bounding boxes onto a page image for visual debugging |