Extract tags from PDFs

To extract tags from PDFs, the specific meaning of “tags” can vary depending on context. Below are common interpretations and how to extract each:

1. Extracting Metadata Tags (e.g., author, title, subject)

These are embedded metadata fields in a PDF file.

Python with PyPDF2:

python
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from PyPDF2 import PdfReader

reader = PdfReader("your_file.pdf")
metadata = reader.metadata
for key, value in metadata.items():
    print(f"{key}: {value}")

2. Extracting Structural Tags (Tagged PDFs for accessibility)

Tagged PDFs use a structured tree for accessibility (like headings, paragraphs, etc.).

Using pdfminer.six:

bash
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pip install pdfminer.six

python
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from pdfminer.high_level import extract_text
text = extract_text("your_file.pdf")
print(text)

Note: pdfminer doesn’t expose tag structures like <H1>, <P> directly, but it retrieves the readable text. For actual tag trees (like StructureTreeRoot), you’d need a lower-level parser or PDF library like PDFix SDK or Adobe Acrobat SDK.

3. Extracting Custom Keyword Tags (embedded via properties or annotations)

If tags are embedded as keywords in the document properties:

Python with PyMuPDF (fitz):

python
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import fitz  # PyMuPDF

doc = fitz.open("your_file.pdf")
metadata = doc.metadata
print(metadata.get("keywords"))  # Custom keyword tags

4. Extracting Text-Based Hashtags or Annotations (e.g., #AI, #Tech)

For hashtags or in-text labels:

python
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import re
from pdfminer.high_level import extract_text

text = extract_text("your_file.pdf")
tags = re.findall(r"#w+", text)
print(set(tags))

Tools Without Coding

If you prefer no code:

• Adobe Acrobat Pro: Go to File > Properties > Description to view tags (keywords).

• PDF-XChange Editor: Use Document Info to see metadata.

• Online Tools: Tools like PDF Candy or PDF24 Tools can show metadata but are limited for structural tags.

Let me know your specific use case (metadata tags, structural tags, or hashtags), and I can tailor the method further.