我能够找到一个解决方案，成功地通过PDF迭代，找到信件结尾的文本，然后插入空白页。代码如下。

"""This program will take an input pdf file and search for a string that signifies the end of a letter.
 After the end of the letter is found based on a string, a blank page is added. The output file is then
 created in the directory with blank pages added """

import PyPDF2, re

pdfIn = open('sample_letter.pdf', 'rb')
pdfFile = PyPDF2.PdfFileReader(pdfIn)
NumPages = pdfFile.getNumPages()
string = "Text I am searching for"
output = PyPDF2.PdfFileWriter()
outputStream = open('added_blank_pages.pdf', 'wb')

def end_of_letter():
    pages = []
    for page in range(NumPages):
        pgObj = pdfFile.getPage(page)
        text = pgObj.extractText()
        match = re.search(string, text)
        output.addPage(pgObj)
        if match:
            pages.append(page + 1)
            output.addBlankPage()
    output.write(outputStream)
    print(pages)

end_of_letter()

我知道这个问题是专门针对pyPDF2的，但我使用的是不同的PDF库pikepdf，它对我来说更快，我想分享我的代码：

import pikepdf
import sys

if len(sys.argv) == 1:
    exit("No File provided")
with pikepdf.open(sys.argv[1], allow_overwriting_input=True) as pdf:
    print(f"Editing {sys.argv[1]}")
    length = len(pdf.pages)
    pdf.add_blank_page(page_size=(pdf.pages[0]["/MediaBox"][2], 
        pdf.pages[0]["/MediaBox"][3]))
    for i in range(1, 2*length-2, 2):
        print(f"inserting  blank page at {i}")
        pdf.pages.insert(i, pdf.pages[-1])

    pdf.save()

您可以通过以下方式对文件夹中的每个文件执行此操作（PowerShell）：

dir ~/Downloads | ? -Property Extension -eq .pdf | % {py .\addEmpty.py "$_"}

只是想分享一个方法，我用另一个Python库解决了我今天的问题。我在Windows 11上安装了Python 3.10.10。

# Import library
# More, visit https://pypi.org/project/PyMuPDF/
import fitz

# Load input file
doc = fitz.open("file_to_be_edited.pdf")

# You can see the width and height of a pdf file like so
# print('Width: ',doc[0].rect.width,'Height: ',doc[0].rect.height)

# Insert a blank page before page 2, after page 1
# First page starts as 0, not 1
# Width and height are points/pt
# More see https://pymupdf.readthedocs.io/en/latest/document.html#Document.new_page
doc.new_page(pno=1, width=612, height=792)

doc.save("output_file_with_blank_page_inserted.pdf")