有没有办法从PDF中提取无边框表格到CSV？

import tabula

# 读取PDF文件中的表格
df = tabula.read_pdf("input.pdf", pages='all')

# 将表格保存为CSV文件
df.to_csv("output.csv", index=False)

from pdfminer.pdfparser import PDFParser
from pdfminer.pdfdocument import PDFDocument
from pdfminer.pdfpage import PDFPage
from pdfminer.pdfinterp import PDFResourceManager, PDFPageInterpreter
from pdfminer.layout import LAParams, LTTextBox, LTTextLine
from pdfminer.converter import PDFPageAggregator
import csv

def extract_table_from_pdf(pdf_path, csv_path):
    with open(pdf_path, 'rb') as fp:
        parser = PDFParser(fp)
        document = PDFDocument(parser)
        rsrcmgr = PDFResourceManager()
        laparams = LAParams()
        device = PDFPageAggregator(rsrcmgr, laparams=laparams)
        interpreter = PDFPageInterpreter(rsrcmgr, device)
        tables = []
        
        for page in PDFPage.create_pages(document):
            interpreter.process_page(page)
            layout = device.get_result()
            for element in layout:
                if isinstance(element, LTTextBox) or isinstance(element, LTTextLine):
                    text = element.get_text().strip()
                    if text.startswith('|') and text.endswith('|'):
                        rows = text.split('\n')
                        table = [row.strip().split('|')[1:-1] for row in rows]
                        tables.append(table)
        
        with open(csv_path, 'w', newline='') as csvfile:
            writer = csv.writer(csvfile)
            for table in tables:
                writer.writerows(table)

# 调用函数进行提取
extract_table_from_pdf("input.pdf", "output.csv")