求助：如何用PDFMiner.six提取PDF单行文本的字体信息？

Got it, let's work through this! Since you already have basic PDF-to-text extraction up and running, grabbing line-specific font info just means leaning into PDFMiner.six's layout analysis tools—instead of only pulling raw text, we'll interact with the structural objects that hold styling metadata.

How It Works #

PDFMiner breaks down PDFs into a hierarchy of layout objects, and the ones we care about here are:

• LTTextLine: Represents a single line of text
• LTChar: Individual character objects within a line, each carrying font name, size, and other style details

Every line is made up of these LTChar instances, so we can pull font data directly from them.

Step-by-Step Code Example #

First, make sure you're using a pdfminer.six version compatible with Python 3.6.3—install it with:

pip install pdfminer.six==20201018

Then use this code to extract line-level font information:

from pdfminer.high_level import extract_pages
from pdfminer.layout import LTTextContainer, LTTextLine, LTChar
from collections import defaultdict

def extract_line_fonts(pdf_path):
    for page_num, page_layout in enumerate(extract_pages(pdf_path), start=1):
        print(f"--- Page {page_num} ---")
        for element in page_layout:
            # Only process elements that contain text
            if isinstance(element, LTTextContainer):
                for text_line in element:
                    if isinstance(text_line, LTTextLine):
                        line_text = text_line.get_text().strip()
                        if not line_text:
                            continue
                        
                        # Track font usage in the line (handles mixed fonts)
                        font_stats = defaultdict(int)
                        for char in text_line:
                            if isinstance(char, LTChar):
                                # Use (font name, size) as a unique identifier
                                font_key = (char.fontname, round(char.size, 2))
                                font_stats[font_key] += 1
                        
                        # Get the most common font in the line
                        if font_stats:
                            most_common_font = max(font_stats, key=font_stats.get)
                            font_name, font_size = most_common_font
                            print(f"Line: {line_text}")
                            print(f"Font: {font_name}, Size: {font_size}\n")

# Run the function on your target PDF
extract_line_fonts("your_document.pdf")

Key Notes #

• Handling Mixed Fonts: The code tracks all fonts in a line and picks the most common one. If you need to account for multiple fonts in a single line (e.g., bold headings within a regular text line), you can modify it to group characters by their font properties and report each one.
• Precision: Font sizes are rounded to 2 decimal places for readability—adjust the rounding value if you need more precision.
• High-Level API: We use extract_pages() because it simplifies traversing the PDF layout compared to the low-level parser/interpreter setup you might have used for basic text extraction.

This should give you the line-specific font name and size you're looking for. Let me know if you run into edge cases with your specific PDFs!

内容的提问来源于stack exchange，提问作者mrwadepro