eliferjunior/data-extractor

Data Extractor

Overview

Extract structured data from documents in any format: PDF, DOCX, HTML, TXT, images, and more. Converts unstructured or semi-structured content into clean JSON, CSV, or other structured formats. Handles invoices, forms, reports, and free-text documents.

Instructions

When a user asks you to extract data from a document, follow this process:

Step 1: Identify the document format and install dependencies

# Determine file type
file document.pdf

# Install dependencies based on format
pip install pdfplumber python-docx beautifulsoup4 lxml openpyxl

Library selection by format:

• PDF: pdfplumber (text + tables), PyMuPDF (fitz) for complex layouts
• DOCX: python-docx
• HTML: beautifulsoup4 with lxml
• Excel: openpyxl or pandas
• Images: pytesseract (OCR) with Pillow
• JSON/XML: Python standard library

Step 2: Extract raw content

PDF extraction:

import pdfplumber

with pdfplumber.open("document.pdf") as pdf:
    for i, page in enumerate(pdf.pages):
        text = page.extract_text()
        print(f"--- Page {i+1} ---")
        print(text)

        # Extract tables if present
        tables = page.extract_tables()
        for table in tables:
            for row in table:
                print(row)

DOCX extraction:

from docx import Document

doc = Document("document.docx")
for para in doc.paragraphs:
    print(f"[{para.style.name}] {para.text}")

# Extract tables
for table in doc.tables:
    for row in table.rows:
        print([cell.text for cell in row.cells])

HTML extraction:

from bs4 import BeautifulSoup

with open("document.html") as f:
    soup = BeautifulSoup(f, "lxml")

# Extract specific elements
for table in soup.find_all("table"):
    rows = table.find_all("tr")
    for row in rows:
        cells = [td.get_text(strip=True) for td in row.find_all(["td", "th"])]
        print(cells)

Step 3: Parse and structure the data

Once you have raw text, extract the target fields:

Pattern-based extraction:

import re
import json

text = "..."  # extracted text

# Define patterns for common fields
patterns = {
    "invoice_number": r"Invoice\s*#?\s*:?\s*(\w+[-/]?\w+)",
    "date": r"Date\s*:?\s*(\d{1,2}[/-]\d{1,2}[/-]\d{2,4})",
    "total": r"Total\s*:?\s*\$?([\d,]+\.?\d*)",
    "email": r"[\w.-]+@[\w.-]+\.\w+",
}

extracted = {}
for field, pattern in patterns.items():
    match = re.search(pattern, text, re.IGNORECASE)
    if match:
        extracted[field] = match.group(1) if match.lastindex else match.group(0)

print(json.dumps(extracted, indent=2))

Line-item extraction from tables:

import pandas as pd

# From a list of table rows
headers = table_data[0]
rows = table_data[1:]
df = pd.DataFrame(rows, columns=headers)

# Clean up
df.columns = df.columns.str.strip().str.lower().str.replace(" ", "_")
df = df.dropna(how="all")

Step 4: Validate and clean the output

# Type conversion
extracted["total"] = float(extracted["total"].replace(",", ""))

# Date normalization
from datetime import datetime
extracted["date"] = datetime.strptime(extracted["date"], "%m/%d/%Y").isoformat()

# Validate required fields
required = ["invoice_number", "date", "total"]
missing = [f for f in required if f not in extracted]
if missing:
    print(f"Warning: missing fields: {missing}")

Step 5: Output in the desired format

# JSON output
with open("extracted_data.json", "w") as f:
    json.dump(extracted, f, indent=2)

# CSV output
df.to_csv("extracted_items.csv", index=False)

# Pretty print summary
print(f"Extracted {len(extracted)} fields from document")
print(f"Line items: {len(df)} rows")

Examples

Example 1: Extract invoice data from a PDF

User request: "Extract the invoice details from this PDF"

Actions:

1. Open the PDF with pdfplumber and extract text
2. Use regex patterns to find invoice number, date, vendor, subtotal, tax, total
3. Extract the line items table into a DataFrame
4. Output a JSON file with header fields and a CSV with line items

Output:

{
  "invoice_number": "INV-2025-0042",
  "date": "2025-03-15",
  "vendor": "Acme Corp",
  "subtotal": 1250.00,
  "tax": 100.00,
  "total": 1350.00,
  "line_items": [
    {"description": "Widget A", "qty": 10, "unit_price": 75.00, "amount": 750.00},
    {"description": "Widget B", "qty": 5, "unit_price": 100.00, "amount": 500.00}
  ]
}

Example 2: Extract contacts from a DOCX directory

User request: "Pull all names and email addresses from this company directory document"

Actions:

1. Parse the DOCX file, iterate through paragraphs and tables
2. Use regex to find email addresses and associated names
3. Deduplicate and output as CSV

Output: A CSV file with columns: name, email, department, phone.

Example 3: Convert an HTML report to structured data

User request: "Extract the quarterly results table from this HTML page"

Actions:

1. Parse the HTML with BeautifulSoup
2. Find the target table by heading or class
3. Extract headers and rows into a DataFrame
4. Clean column names and convert numeric values
5. Export as CSV and provide summary statistics

Output: A clean CSV with quarterly metrics and a summary of key figures.

Guidelines

• Always inspect the raw extracted text before writing parsers. Understanding the layout saves time.
• Use pdfplumber for most PDF extraction. Fall back to PyMuPDF for complex multi-column layouts.
• For scanned PDFs (image-based), use OCR with pytesseract before parsing.
• Validate extracted data types: convert strings to numbers, normalize dates.
• Report extraction confidence: note any fields that could not be found or seem incorrect.
• Handle multi-page documents by accumulating results across pages.
• For batch extraction (many documents of the same type), build a reusable extraction function and apply it across all files.
• Always preserve the original document alongside extracted data for verification.
• When patterns fail, fall back to positional extraction based on text layout.